spirv: Fix reaching unreachable for compare exchange on images
We were hitting the
unreachable("Invalid image opcode")
near the end of vtn_handle_image when parsing the
SpvOpAtomicCompareExchange opcode.
v2: Add stable CC.
v3: Ignore SpvOpAtomicCompareExchangeWeak. It requires the Kernel
capability which is not exposed in Vulkan, and spirv_to_nir is not used
for OpenCL which does support it.
Reviewed-by:
Jason Ekstrand <jason@jlekstrand.net>
CC: <mesa-stable@lists.freedesktop.org>