[FixCode] Introduce '-fixit-all' option that, when -fixit-code is enabled, applies all fixits from diagnostics without any filtering.

Swift SVN r31772

lib/Frontend/CompilerInvocation.cpp

@@ -865,6 +865,7 @@ static bool ParseDiagnosticArgs(DiagnosticOptions &Opts, ArgList &Args,
   Opts.ShowDiagnosticsAfterFatalError |=
     Args.hasArg(OPT_show_diagnostics_after_fatal);
   Opts.UseColor |= Args.hasArg(OPT_color_diagnostics);
+  Opts.FixitCodeForAllDiagnostics |= Args.hasArg(OPT_fixit_all);
 
   return false;
 }