Revert "Trying to understand the TestHelp.py failure from 6c089b2."

It didn't help.

This reverts commit 81f8788528.

lldb/source/Interpreter/CommandAlias.cpp

@@ -180,7 +180,7 @@ bool CommandAlias::IsDashDashCommand() {
 
   for (const auto &opt_entry : *GetOptionArguments()) {
     std::tie(opt, std::ignore, value) = opt_entry;
-    if (opt == "<argument>" && !value.empty() &&
+    if (opt == CommandInterpreter::g_argument && !value.empty() &&
         llvm::StringRef(value).endswith("--")) {
       m_is_dashdash_alias = eLazyBoolYes;
       break;