shader code creation may emit 'invariant' for geometry shaders, but this is illegal if the input is not invariant

One failing piglit is: spec/glsl-1.50/execution/invariant-qualifier-everywhere.shader_test

error: vertex shader output `vso_g9' has invariant qualifier, but geometry shader input lacks invariant qualifier 
error: vertex shader output `vso_g10' has invariant qualifier, but geometry shader input lacks invariant qualifier