This flag tracks whether or not cooperative matrices are fully enabled
on the physica device (i.e., both the configs exist and the environment
varible is set). This is mainly to support a later commit "anv: Set
PIPELINE_SELECT systolic mode enable flag."
This could be squashed into "anv: Implement VK_KHR_cooperative_matrix."
I left it separate because we might go back to the previous method.
v3: Don't hide the extension behind an environment variable
(ANV_COOPERATIVE_MATRIX) now the we have a better solution for setting
PIPELINE_SELECT.
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25994>
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