nir/instr_set: hash intrinsic sources

nir/instr_set: hash intrinsic sources

ministat (CSE only):
Difference at 95.0% confidence
	-9.80325 +/- 0.173089
	-41.4434% +/- 0.461972%
	(Student's t, pooled s = 0.0763653)

ministat (entire run):
Difference at 95.0% confidence
	-3.13667 +/- 0.61519
	-5.11107% +/- 0.990737%
	(Student's t, pooled s = 0.271416)

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6860>