glsl: don't allow invariant qualifiers for interface blocks

glsl: don't allow invariant qualifiers for interface blocks

GLSL 1.50 and GLSL 4.40 specs, they both say the same in
"Interface Blocks" section:

"If optional qualifiers are used, they can include interpolation qualifiers,
auxiliary storage qualifiers, and storage qualifiers and they must declare
an input, output, or uniform member consistent with the interface qualifier
of the block"

From GLSL ES 3.0, chapter 4.3.7 "Interface Blocks", page 38:

"GLSL ES 3.0 does not support interface blocks for shader inputs or outputs."

and from GLSL ES 3.0, chapter 4.6.1 "The invariant qualifier", page 52.

"Only variables output from a shader can be candidates for invariance."

This patch fixes the following dEQP tests:

dEQP-GLES3.functional.shaders.declarations.invalid_declarations.invariant_uniform_block_2_vertex
dEQP-GLES3.functional.shaders.declarations.invalid_declarations.invariant_uniform_block_2_fragment

No piglit regressions.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
v2:

- Enable this check for GLSL.

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>