Makes for easier reading of the assertion macros.

Bug: b/148401179
Change-Id: Icc48baa9c476967c6dea19c2f0e91ed253dce323
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/42194Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>