glsl: Modify array_sizing_visitor to handle unnamed interface blocks.

We were already setting the array size of unsized arrays that appeared
inside unnamed interface blocks, but we weren't updating
ir_variable::interface_type to reflect the new array size, causing
bogus link errors.

This patch causes array_sizing_visitor to keep track of all the
unnamed interface types it sees, and the ir_variables corresponding to
each one.  After the visitor runs, a new function,
fixup_unnamed_interface_types(), adjusts each unnamed interface type
to correctly correspond with the array sizes in the ir_variables.

Fixes piglit tests:
- spec/glsl-1.50/execution/unsized-in-unnamed-interface-block-gs
- spec/glsl-1.50/execution/unsized-in-unnamed-interface-block-multiple