Update SPIRV-Tools for O1experimental VariablePointers cleanup

Pull in the companion SPIRV-Tools change that adds a dedicated
TrimVariablePointersCapabilitiesPass at the end of the O1experimental fast
performance recipe.

The follow-up fixes a real sampler regression where the final optimized
module still carried stale VariablePointers / VariablePointersStorageBuffer
capability declarations even though the final IR no longer contained the
pointer forms that required them. The failing EX37 shader remained
validator-legal and had only scalar OpSelect %float, but removing only
those stale capability lines fixed the downstream runtime corruption.

Keep the default trim path untouched by keeping the cleanup isolated to the
experimental fast path in SPIRV-Tools.

Author: AnastaZIuk