Dawn tests use shaderc, which assumes glslang has HLSL support.  This
change makes HLSL support also follow template arguments, and changes
the target names such that glslang_sources will remain the "has all
features" target and the new glslang_lib_sources would be what ANGLE
would use.
Signed-off-by: Shahbaz Youssefi <ShabbyX@gmail.com>