8162546: change hidden options -Xdebug to --debug, -XshouldStop to --should-stop, and -diags to --diags
Reviewed-by: mcimadamore

8161019: javac, fold formatter options
Reviewed-by: mcimadamore, jjg

8078024: javac, several incorporation steps are silently failing when an error should be reported
Reviewed-by: mcimadamore