i965: Copy shader->shadow_samplers to prog->ShadowSamplers.

i965: Copy shader->shadow_samplers to prog->ShadowSamplers.

ir_to_mesa does this - apparently we just forgot or something.

Without this, we'll guess the wrong texture swizzle (XYZW for color
instead of XXX1 for depth) when doing precompiles.

This cuts 26 shader recompiles in a time demo of "Counter Strike:
Global Offensive" (58 -> 32) on Sandybridge.  Haswell still has 0
recompiles.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=87886
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>