glslangValidator: Add straightforward SPIR-V support (non-optimizing, ~3.x functionality): fix linux case issue.

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@30033 e7fa87d3-cd2b-0410-9028-fcbf551c1848