SPV: Split loop header from condition testing for for/while loops.

SPV: Don't remove SPIR-V blocks before codegen, use new InReadableOrder instead.

A removed block releases its instructions, so Module::idToInstruction
suddenly contains dangling references.  The original motivation for
block removal was to skip some unreachable blocks, but that's already
achieved by InReadableOrder.cpp.

Also updated stale comments.

SPV: Rework loop code generation to match SPIR-V 1.0.

SPV: Code-generate SPIR-V blocks in a more readable order

Add a test for unreachable merge block.

Update test results with the new order: mainly delaying merge blocks and
removing unreachable ones.

Freed up some command line memory (not used programmatically).

Free memory associated with SPIR-V generation and the pragmaTable.

Separating file I/O from compile/link lets the compile/link be done
repeatedly in a loop for testing and measuring of performance and
memory footprint, including seeing memory growth over time for
functional-level memory-leak testing.

While the older compile-only mode already had this functionality,
and typically showed no memory leaks, SPIR-V uses the link path,
has pending "TODO" for memory freeing, and this shows several
kilobytes of leaking per compile-link. Most likely, pending
merge request 131 will address much of this.

Parser & SPV: Implement two extensions regarding GLSL sparse texture.

Preprocessor: Removed strcpy that copied a value to itself.

Fix several build warnings/error encountered with VS2013

linkValidate: Round up structure sizes to vec4 in std140

The argument version is passed in from above and struct handling ensures
that row-majorness gets propagated correctly from one level to the next.
If we just look at the type itself and it's embedded in a struct that's
declared row-major, we may get the wrong stride.

Found by running glslang with -fsanitize=address in clang.
Also fixes a potential buffer-overrun with return from lReadByte.

Change-Id: Ie8236430bb9e30a9be2e0c1573c42183c2f4d0d4

To ensure back branches always go to a header block, create a header
block even for !testFirst loops.  Then unify common code between the
testFirst/!testFirst cases.

Generate the header-block code first, so update golden files.

Realize that certain infinite loops generate invalid SPIR-V, so put a
TODO to instead abort code generation in such cases.

Change-Id: I1e173c8f73daad186cfc666b7d72bd563ed7665d