glsl linker: support arrays of interface block instances

glsl linker: support arrays of interface block instances

With this change we now support interface block arrays.
For example, cases like this:

out block_name {
    float f;
} block_instance[2];

This allows Mesa to pass the piglit glsl-1.50 test:
* execution/interface-blocks-complex-vs-fs.shader_test

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>