intel/blorp: Fix usage of uninitialized memory in key hashing v2
I broke i965 in !2552 (merged) and it was reverted.
Now I made i965/brw_program_cache.c
handle keys with size that is not multiply of 4, using the same hash method as Iris and ANV.
Now it passes CI: https://mesa-ci.01.org/global_logic/builds/229/group/63a9f0ea7bb98050796b649e85481845