glsl: call nir_opt_find_array_copies() when linking

glsl: call nir_opt_find_array_copies() when linking

shader-db results IRIS (BDW):

total instructions in shared programs: 17883388 -> 17859658 (-0.13%)
instructions in affected programs: 48100 -> 24370 (-49.33%)
helped: 6
HURT: 0
helped stats (abs) min: 1450 max: 7028 x̄: 3955.00 x̃: 3387
helped stats (rel) min: 40.31% max: 51.92% x̄: 47.07% x̃: 48.96%
95% mean confidence interval for instructions value: -6613.28 -1296.72
95% mean confidence interval for instructions %-change: -52.73% -41.40%
Instructions are helped.

total cycles in shared programs: 866961809 -> 863521521 (-0.40%)
cycles in affected programs: 9179396 -> 5739108 (-37.48%)
helped: 6
HURT: 0
helped stats (abs) min: 252584 max: 972430 x̄: 573381.33 x̃: 495130
helped stats (rel) min: 21.80% max: 48.65% x̄: 35.01% x̃: 34.58%
95% mean confidence interval for cycles value: -917157.00 -229605.67
95% mean confidence interval for cycles %-change: -47.61% -22.40%
Cycles are helped.

total spills in shared programs: 20417 -> 15521 (-23.98%)
spills in affected programs: 6966 -> 2070 (-70.28%)
helped: 6
HURT: 0

total fills in shared programs: 25151 -> 21005 (-16.48%)
fills in affected programs: 4374 -> 228 (-94.79%)
helped: 6
HURT: 0

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/9055
Fixes: d75a36a9eeb1 ("glsl: remove do_copy_propagation_elements() optimisation pass")

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23737>