Remove -suppress-argument-labels-in-types; it's dead.

lib/Frontend/CompilerInvocation.cpp

@@ -789,9 +789,6 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
       = A->getOption().matches(OPT_enable_testable_attr_requires_testable_module);
   }
 
-  Opts.SuppressArgumentLabelsInTypes |=
-    Args.hasArg(OPT_suppress_argument_labels_in_types);
-
   if (const Arg *A = Args.getLastArg(OPT_debug_constraints_attempt)) {
     unsigned attempt;
     if (StringRef(A->getValue()).getAsInteger(10, attempt)) {