Fix glGet with enums which are used not only in NV_vertex_program, but other extensio...

Fix glGet with enums which are used not only in NV_vertex_program, but other extensions too (ARB_vertex_program, ARB_fragment_program, NV_fragment_program), if no support for NV_vertex_program is present. While here, fix return value if enum is used which is not supported by the exposed extensions (GL_INVALID_ENUM instead of GL_INVALID_VALUE). Fix some compile-time #ifs depending on NV_vertex/fragment_program which should also be dependant on ARB_vertex/fragment_program. See bug #6070