SamplerFunction can then be passed to RR_LOG and RR_WATCH.

Bug: b/140287657
Change-Id: If37d99469b7df98b539430abdcd184eec81bc08f
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/33471Tested-by: Ben Clayton <bclayton@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>