util/set: Use fast modulo computation

Compilation times with my shader-db database:

Difference at 95.0% confidence
	-1.22312 +/- 0.726033
	-0.283979% +/- 0.168254%
	(Student's t, pooled s = 1.02177)

Reviewed-by: Eric Anholt <eric@anholt.net>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
2 files changed