glsl/linker: Modify array_sizing_visitor to handle named interface blocks.

glsl/linker: Modify array_sizing_visitor to handle named interface blocks.

Unsized arrays appearing inside named interface blocks now get a
proper size assigned by the array_sizing_visitor.

Fixes piglit tests:
- spec/glsl-1.50/execution/unsized-in-named-interface-block
- spec/glsl-1.50/execution/unsized-in-named-interface-block-gs
- spec/glsl-1.50/linker/unsized-in-named-interface-block
- spec/glsl-1.50/linker/unsized-in-named-interface-block-gs
- spec/glsl-1.50/linker/unsized-in-unnamed-interface-block-gs (*)

(*) is fixed by dumb luck--support for unsized arrays in unnamed
interface blocks will come in a later patch.

Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>