The idea is that for repeated use of the same uniform, we could avoid
loading it on each consumer.  The results look pretty good.

total instructions in shared programs: 6413571 -> 6521464 (1.68%)
total threads in shared programs: 154214 -> 154000 (-0.14%)
total uniforms in shared programs: 2393604 -> 2119629 (-11.45%)
total spills in shared programs: 4960 -> 4984 (0.48%)
total fills in shared programs: 6350 -> 6418 (1.07%)

Once we do scheduling at the NIR level, the register pressure (and thus
also instructions) issues we see here will drop back down.