Basic SSA Validation

Most uses of an ID must occur after the definition
of the ID.  Forward references are allowed for
things like OpName, OpDecorate, and various cases
of control-flow instructions such as OpBranch, OpPhi,
and OpFunctionCall.

TODO: Use CFG analysis for SSA checks.  In particular,
an ID defined inside a function body is only usable inside
that function body.  Also, use dominator info to catch
some failing cases.

Also:
* Validator test cases use (standard) assignment form.
* Update style to more closely follow the Google C++ style guide
* Remove color-diagnostics flag.
  This is enabled by default on terminals with color. Prints
  hidden ASCII for terminals that can't handle color(Emacs)
* Pass functors to SSAPass to check if the
  operand can be forward referenced based on its index value
* Return SPV_ERROR_INVALID_ID for ID related errors
  spvBinaryParse returned SPV_ERROR_INVALID_BINARY for all types of
  errors. Since spvBinaryParse does some ID validation, this was
  returning inappropriate error codes for some tests.
* Common fixture for validation tests.
  It only runs certian validation passes.
* Add a SPV_VALIDATE_SSA_BIT for testing purposes
* Fixtures now return error codes
* Add OpName support in diag message and unit tests
* Binary parsing can fail with invalid ID or invalid binary error code

Tests include:
* OpDecorate
* OpName
* OpMemberName
* OpBranchConditional
* OpSelectionMerge
* OpMemberDecorate
* OpGroupDecorate
* OpDeviceEnqueue
* Enable several tests failing in ID validation.

1 files changed, 3 insertions, 0 deletions

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 build*
 .ycm_extra_conf.py*
 compile_commands.json
+/external/googletest/
+/TAGS
+/.clang_complete