Track what ins/outs/uniforms are used, so that errors like "declare after use" or "can't use both XXX and YYY" can be issued.  So far, used this for invariant, gl_FragColor et. al., and gl_FragCoord use before redeclaration.

Also made all tests in testlist include linker tests.


git-svn-id: https://cvs.khronos.org/svn/repos/ogl/trunk/ecosystem/public/sdk/tools/glslang@24156 e7fa87d3-cd2b-0410-9028-fcbf551c1848