glsl/glcpp: Fix glcpp-test to correctly extract test-specific arguments

glsl/glcpp: Fix glcpp-test to correctly extract test-specific arguments

The (optional) test-specific command-line arguments to be passed to glcpp are
embedded within the source files of some tests, and glcpp-test uses grep to
extract them.

Of course, grep is line-based and looks for the native line-separator to
determine line boundaries. So, for files using non-native line separators,
grep was getting quite confused and passing bogus arguments to glcpp.

Fix this by canonical-izing the line separators in the source file prior to
using grep.

With this commit, the glcpp-test-cr-lf tests pass entirely:

	\r:	143/143 tests pass
	\r\n:	143/143 tests pass
	\n\r:	143/143 tests pass

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>