Copybara creates Gerrit changes containing a PiperOrigin-RevId: line
when importing from Piper, so accept that instead of a Bug: line.

Bug: b/148537471
Change-Id: I2c655c90c2873787054db4de22bf2f9c3526bdce
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/40731
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Antonio Maiorano <amaiorano@google.com>