Revert 3264 combo build back to warning (backout 7061112), warning to be parsed by RE.

RE has implemented code for windows-i586 builds to parse and wait for up to three hours for the windows-amd64 build to complete, and then rerun the 3264 combo installer target. If the three hours is exceeded, RE will present a hard failure.

By reverting to a warning on the combo installer, it's possible to recover from a failed combo installer by just rerunning the target post windows-i586 build. Still should be a rare occurance, only happening for a hard failure on windows-amd64.