Basic/Diagnostic: Factor out
DiagnosticsEngine::setDiagnosticGroup{ErrorAsFatal,WarningAsError} methods which
more accurately model the correct API -- no internal change to the diagnostics
engine yet though.
 - Also, stop honoring -Werror=everything (etc.) as a valid (but oddly behaved) option.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@140747 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed