zink: fix gpl lib hashing

zink: fix gpl lib hashing

this was including the generated tcs bits, which was likely to be wrong
and thus break optimal key hashing, requiring more pipelines

it also wasn't setting the optimal key value correctly during precompile,
which meant the wrong hash value was used and the precompiled libs were never
actually accessible

cc: mesa-stable

Reviewed-by: Emma Anholt <emma@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21169>
(cherry picked from commit 4cf54e2ed22023c986f70711bddd0e934aa5683c)