Teach filter-build-webkit about XCBuild build output that needs to be reformatted. At the same time, address other red messages that have crept in over time, either reformatting or squelching them. Some red messages are still emitted under both XCBuild and the Legacy build system, but those either need to be addressed at the source or be investigated first in order to determine the correct remediation. rdar://problem/63819507
Created attachment 406421 [details] Patch
Committed r265526: <https://trac.webkit.org/changeset/265526> All reviewed patches have been landed. Closing bug and clearing flags on attachment 406421 [details].