[clang] Fix -fsanitize-system-blacklist processing in cc1

clang/lib/Frontend/CompilerInvocation.cpp

@@ -3194,6 +3194,11 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   Opts.SanitizeAddressFieldPadding =
       getLastArgIntValue(Args, OPT_fsanitize_address_field_padding, 0, Diags);
   Opts.SanitizerBlacklistFiles = Args.getAllArgValues(OPT_fsanitize_blacklist);
+  std::vector<std::string> systemBlacklists =
+      Args.getAllArgValues(OPT_fsanitize_system_blacklist);
+  Opts.SanitizerBlacklistFiles.insert(Opts.SanitizerBlacklistFiles.end(),
+                                      systemBlacklists.begin(),
+                                      systemBlacklists.end());
 
   // -fxray-instrument
   Opts.XRayInstrument =