Regres: Don't attempt to build failing changes forever.

Regres: Don't attempt to build failing changes forever.

If a test failed to build, an error was logged to stdout, but the error was not posted to the change. This meant the change would be picked up by regres again, and the process would repeat ad-infinitum.

Posting of the build error used to work, but was broken by bfaf4e825b.

Change-Id: I1e59f0d2e5ee26eb002aa2c596dc5491e48a9c87
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/27169
Tested-by: Ben Clayton <bclayton@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>