linker: Accurately mark a uniform block instance array element as used in a stage

linker: Accurately mark a uniform block instance array element as used in a stage

Now that information about which array-of-arrays elements are accessed
is tracked, use that information to only mark an instance array element
as used-by-stage if, in fact, it is.

Fixes GL45-CTS.program_interface_query.uniform-block-types.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>