glsl: Add an ir_variable::max_ifc_array_access field.

glsl: Add an ir_variable::max_ifc_array_access field.

For interface blocks that contain arrays, this field will contain the
maximum element of each contained array that is accessed by the
shader.  This is a first step toward supporting unsized arrays in
interface blocks.

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