Allow gl_FragColor and gl_FragData in non-forward-compatible contexts for non-ES versions 150 - 410. Also add deprecation message for attribute/varying for core profile.

git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@20714 e7fa87d3-cd2b-0410-9028-fcbf551c1848