* Fix type conversion warnings.

Fixes #949

Tested locally (Linux/clang), but warnings are on MSVC so may differ.

* Drop the ULP so the double test passes

Line "- /usr/local/bin:$PATH" is misformatted.
It must be something like "- PATH=/usr/local/bin:$PATH".

It seems something changed in tarvis-ci month ago and now this leads to:

Setting environment variables from .travis.yml
$ export PATH=

Defailt PATH is /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin
so already containts /usr/local/bin.


Image "xcode8.3" contains macOS 10.12 (sierra) which has no bottles
with precompiled gcc-7 in homebrew storage.

Image "xcode9.4" is a current default with macOS 10.13 (high_sierra).

Link: https://docs.travis-ci.com/user/reference/osx/
Link: https://formulae.brew.sh/formula/gcc@7Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>

This reverts commit 5ce2429a.

Reverts https://github.com/google/benchmark/pull/923
Reopens https://github.com/google/benchmark/issues/922
Fixes https://github.com/google/benchmark/issues/928
Closes https://github.com/google/benchmark/pull/930

See discussion in https://github.com/google/benchmark/issues/928
this broke pkg-config support, since there we don't account
for the suffix, nor is it trivial to do so.

This reverts commit 5ce2429a.

Reverts https://github.com/google/benchmark/pull/923
Reopens https://github.com/google/benchmark/issues/922
Fixes https://github.com/google/benchmark/issues/928
Closes https://github.com/google/benchmark/pull/930

See discussion in https://github.com/google/benchmark/issues/928
this broke pkg-config support, since there we don't account
for the suffix, nor is it trivial to do so.

* Add State::error_occurred()

* Relax CHECK condition in benchmark_runner.cc

If the benchmark state contains an error, do not expect any iterations has been run.
This allows using SkipWithError() and return early from the benchmark function.

* README.md: document new possible usage of SkipWithError()

This fixes the Visual Studio 2019 warning:

`C4244: '=': conversion from 'int' to 'char', possible loss of data`

When implicitly casting the return value of tolower() (int) to char.

Fixes: #932

* add Jordan Williams to both CONTRIBUTORS and AUTHORS

* alias benchmark libraries

Provide aliased CMake targets for the benchmark and benchmark_main targets.
The alias targets are namespaced under benchmark::, which is the namespace when they are exported.
I chose not to use either the PROJECT_NAME or the namespace variable but to hard-code the namespace.
This is because the benchmark and benchmark_main targets are hard-coded by name themselves.
Hard-coding the namespace is also much cleaner and easier to read.

* link to aliased benchmark targets

It is safer to link against namespaced targets because of how CMake interprets the double colon.
Typo's will be caught by CMake at configuration-time instead of during compile / link time.

* document the provided alias targets

* add "Usage with CMake" section in documentation

This section covers linking against the alias/import CMake targets and including them using either find_package or add_subdirectory.

* format the "Usage with CMake" README section

Added a newline after the "Usage with CMake" section header.
Dropped the header level of the section by one to make it a direct subsection of the "Usage" section.
Wrapped lines to be no longer than 80 characters in length.

* Add DEBUG_POSTFIX to libraries.

Makes it possible to install Debug and Release versions on the
same system. Without this, there were only linker errors when using
the wrong configuration.

* Update CONTRIBUTORS and AUTHORS according to guide

As disscussed in https://github.com/google/benchmark/issues/899,
it is all but certain that the multiplier should be 1024, not 1000.

Fixes https://github.com/google/benchmark/issues/899

See https://github.com/google/benchmark/issues/881

Fix some issues seen in some static analysis reports

Higher up we dereference argc only if it is not null.
But here we do no such check.

From clang-tidy bugprone-incorrect-roundings check:
> casting (double + 0.5) to integer leads to incorrect rounding; consider using lround (#include <cmath>) instead

From clang-tidy bugprone-incorrect-roundings check:
> casting (double + 0.5) to integer leads to incorrect rounding; consider using lround (#include <cmath>) instead

* CTest must use proper paths to executables

With the following syntax:

```
  add_test(NAME <name> COMMAND <command> [<arg>...])
```

if `<command>` specifies an executable target it will automatically
be replaced by the location of the executable created at build time.

This is important if a `<Configuration>_POSTFIX` like `_d` is used.

* Fix typo in ctest invocation

Instead of `-c` the uppercase `-C` must be used to select a config.
But better use the longopt.

Cache size is already stored in bytes.

When building on Windows with `BUILD_SHARED_LIBS=ON`, the symbols were
not being properly exported in the DLL. Fix this by setting
`CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS`.

Fixes #888 

Initialize option flags from environment variables values if they are defined, eg. `BENCHMARK_OUT=<filename>` for `--benchmark_out=<filename>`. Command line flag value always prevails.

Fixes https://github.com/google/benchmark/issues/881.

While I'm here, format all of the files that I touched.

When cross-compiling, this variable was not set on the second run
of CMake, resulting in the next check failing even though it shouldn't
be run in the first place. Fix this by caching the variable.

* fixed the param order in g++ command and fixed the path for -L

* reorder the parameters for g++ command

This macro is sometimes already defined and redefining it results
in build errors.

These OS's don't always have HOST_NAME_MAX defined, resulting in
build errors.

A few related changes as well:
* Only define HOST_NAME_MAX if it's not already defined. There are
  some cases where this is already defined, e.g. with NaCl if
  __USE_POSIX is set. To avoid all of these, only define it if it's
  not already defined.
* Default HOST_NAME_MAX to 64 and issue a #warning. Having the wrong
  max length is pretty harmless. The name just ends up getting
  truncated and this is only for printing debug info. Because we're
  constructing a std::string from a char[] (so defined length), we
  don't need to worry about gethostname's undefined behavior for
  whether the truncation is null-terminated when the hostname
  doesn't fit in HOST_NAME_MAX. Of course, this doesn't help people
  who have -Werror set, since they'll still get a warning.

* Fix missing paren in README code sample, and fix code spacing.

* Add Colin Braley to AUTHORS and CONTRIBUTORS.

* Guard ASSERT_THROWS checks with BENCHMARK_HAS_NO_EXCEPTIONS

This allows the test be run with exceptions turned off

* Add myself to CONTRIBUTORS

I don't need to be added to AUTHORS, as I am a Google employee

* Update with instructions to build under Visual Studio

Fixes Issue #634.

I spent 3 days trying to build this library under Visual Studio 2017, only to discover on has to link to `Shlwapi.lib`.

Became so frustrated with the docs that I added full build instructions for Visual Studio 2015, 2017 and Intel Comiler 2015 and 2019.

* Update headings

In `cmake/GoogleTest.cmake`, GOOGLETEST_PATH is default-initialized, but that init forgot to
account for the fact that the patch is explicitly supposed to be user-configurable.
By passing `CACHE` to `set()` we avoid that error.

- Adresses : #856

  - The unused `doc` argument was removed from the `DEFINE_` macros in
    `commandlineflags.h`

  - Converted all the previous `doc` strings passed to the `DEFINE_`
    macros to multiline comments.

- Addresses : #858

  - Rule `*.swp` is added to `.gitignore` to ensure that the vim temporary
    `.swp` backup files are ignored and they don't pollute the results of
    `git status -u`.

Documentation of basic use of `DenseRange` was added to README.md.

VS2013 is unsupported since https://github.com/google/benchmark/pull/691 / https://github.com/google/benchmark/commit/eb8cbec0776455463274ea9947ab0ecfe0f768fe
but i forgot to update docs.
References:
* https://github.com/google/benchmark/issues/689
* https://github.com/google/benchmark/pull/691
* https://github.com/google/googletest/pull/1815
* https://github.com/google/benchmark/issues/853
* https://github.com/google/benchmark/pull/854