The driver enables -fdiagnostics-show-option by default, so flip the CC1
default to reduce the lengths of common CC1 command lines.
This change also makes ParseDiagnosticArgs() consistently enable
-fdiagnostics-show-option by default.
- The TextDiagnosticPrinter code is still fragile as it is just "reverse engineering" what the diagnostic engine is doing. Not my current priority to fix though.
llvm-svn: 140752