Noticed missing header when was building llvm with gcc-11:

```
llvm-project/llvm/utils/benchmark/src/benchmark_register.h:17:30:
  error: 'numeric_limits' is not a member of 'std'
   17 |   static const T kmax = std::numeric_limits<T>::max();
      |                              ^~~~~~~~~~~~~~
```

Without this commit, compilation fails on DragonFly with the following message:

```
/home/mneumann/Dev/benchmark.old/src/sysinfo.cc:446:2: error: #warning "HOST_NAME_MAX not defined. using 64" [-Werror=cpp]
^~~~~~~
```

Also note that the sysctl is actually `hw.tsc_frequency` on DragonFly:

```
$ sysctl hw.tsc_frequency
hw.tsc_frequency: 3498984022
```

Tested on:

```
$ uname -a
DragonFly box.localnet 5.9-DEVELOPMENT DragonFly v5.9.0.742.g4b29dd-DEVELOPMENT #5: Tue Aug 18 00:21:31 CEST 2020
```

As per discussions in here [1], LLVM is going to get backend support on
Motorola 68000 series CPUs (a.k.a M68K or M680x0). So it's necessary to
add CycleTimer implementation here, which is simply using `gettimeofday`
same as MIPS. This fixes #1049

[1] https://reviews.llvm.org/D88389

NOTE: This is a fresh-start of #738  pull-request which I messed up by re-editing the commiter email which I forgot to modify before pushing. Sorry for the inconvenience.

This PR brings proposed solution for functionality described in #737 

Fixes #737.

Signed-off-by: Vitaly Zaitsev <vitaly@easycoding.org>

* Fix setup.py and reformat

* Bind benchmark

* Add benchmark option to Python

* Add Python examples for range, complexity, and thread

* Remove invalid multithreading in Python

* Bump Python bindings version to 0.2.0
Co-authored-by: Dominic Hamon <dominichamon@users.noreply.github.com>

* Initial version to try to run python bindings example

* python indent issue in setup.py

* better naming

* Bind Counter to Python

* Bind State methods to Python

* Bind state.counters to Python

* Import _benchmark.Counter

* Add Python example of state usage
Co-authored-by: Dominic Hamon <dominichamon@users.noreply.github.com>

* Create pylint.yml

* improve file matching

* fix some pylint issues

* run on PR and push (force on master only)

* more pylint fixes

* suppress noisy exit code and filter to fatals

* add conan as a dep so the module is importable

* fix lint error on unreachable branch

Revert previous linker additions for FreeBSD as the problem is Bazel using /usr/bin/clang instead of /usr/bin/clang++ to link C++ code. (#1035)

* Adds -lm linker flag for (Free|Open)BSD and uses github.com/bazelbuild/platforms for platform detection.

* Prefer selects.with_or to select the linkopts.

* @platforms appears to be implicitly available. @bazel_skylib would require updating every dependent repository.

* Re-enable platforms package.

Fixes #974. The `cxx_feature_check` now has an additional
optional argument which can be used to supply extra cmake flags
to pass to the `try_compile` command. The `CMAKE_CXX_STANDARD=14`
flag was determined to be the minimum flag necessary to correctly
compile and run the regex feature checks when compiling with Clang
under Windows (n.b. this does *not* refer to clang-cl, the frontend
to the MSVC compiler). The additional flag is not enabled for any
other compiler/platform tuple.

* Add CartesianProduct with associated test

* Use CartesianProduct in Ranges to avoid code duplication
* Add new cartesian_product_test to CMakeLists.txt
* Update AUTHORS & CONTRIBUTORS

* Rename CartesianProduct to ArgsProduct

* Rename test & fixture accordingly
* Add example for ArgsProduct to README

* ctest is now working

* Update README

* remove commented out lines

* Tweaked docs

Added note to use parallel and cleaned build config notes

* Response to comments

* revert all but the readme

* make error message clearer

* drop --parallel

Build instructions needlessly referred to make when CMake offers
a command-line interface to abstract away from the specific build
system.

Furthermore, CMake offers command-line "tool mode" which performs basic
filesystem operations. While the syntax is a bit more verbose than
Linux commands it is platform-independent. Now the commands can be
copy-pasted on both Linux and Windows and will just work.

Finally, the Release build type is included in initial commands. A natural flow
for a new-comer is to read and execute the commands and only then learn
that one has to go back and redo them again this time with proper parameters.
Now instead the parameters are only explained later but present already in the
initial commands.

As noted in #995, this causes issues when the command line flag already
starts with "benchmark_", which they all do.

Not caught by tests as the test flags didn't start with "benchmark".

Fixes #995

First attempt at a non-travis/non appveyor CI solution

* JSONReporter: don't report on scaling if we didn't get it (#1005)

* JSONReporter: fix due to review (std::pair<bool, bool> -> enum)

* JSONReporter: scaling: fix the algo (due to review discussion)

* benchmark.h: revert to old-fashioned enum's (C++03 compatibility); rreporter_output_test: let's skip scaling

A few people have complained that `benchmark` is too generic. Also, add
Python 3.8.

* add requirements.txt for python tools

* adds documentation for requirements.txt

Adds installation instructions for python dependencies using pip and requirements.txt

timers: silence format overflow warning

* timestamp: use rfc3339-formatted timestamps in output

Replace localized timestamps with machine-readable IETF RFC 3339 format
timestamps. This is an attempt to make the output timestamps easily
machine-readable. ISO8601 specifies standards for time interchange
formats. IETF RFC 3339: https://tools.ietf.org/html/rfc3339 defines a
subset of these for use in the internet. The general form for these
timestamps is:

YYYY-MM-DDTHH:mm:SS[+-]hhmm

This replaces the localized time formats that are currently being used
in the benchmark output to prioritize interchangeability and
machine-readability.

This might break existing programs that rely on the particular date-time
format. This might also may make times less human readable. RFC3339 was
intended to balance human readability and simplicity for machine
readability, but it is primarily intended as an internal representation.

* timers: remove utc string formatting

We only ever need local time printing. Remove the UTC printing
and cosnolidate the logic slightly.

* timers: manually create rfc3339 string

The C++ standard library does not output the time offset in RFC3339
format, it is missing the : between hours and minutes. VS does not
appear to support timezone information by default. To avoid adding too
much complexity to benchmark around timezone handling e.g. a full
date library like https://github.com/HowardHinnant/date, we fall back
to outputting GMT time with a -00:00 offset for those cases.

* timers: use reentrant form for localtime_r & tmtime_r

For non-windows, use the reentrant form for the time conversion
functions.

* timers: cleanup

Use strtol instead of brittle moving characters around.

* timers: only call strftime twice.

Also size buffers to known maximum necessary size and name constants
more appropriately.

* timers: fix unused variable warning

* Use ==/!= to compare constant literals (str, bytes, int, float, tuple)

Avoid Syntax Warning on Python 3.8: `3 is 3`  # —> Syntax Warning

* Delete mingw.py

* Add Python bindings.

* Add license headers.

* Change example to a test.

* Add example usage to module docstring.