[rebranch][lldb] Fix syntax error

1457b7d introduced
`GetDemangledFunctionNameWithoutArguments` for `SwiftLanguage` but had a
mismatched parenthesis. Remove it.

Author: bnbarham

lldb/source/Plugins/Language/Swift/SwiftLanguage.cpp

@@ -1494,7 +1494,7 @@ ConstString SwiftLanguage::GetDemangledFunctionNameWithoutArguments(Mangled mang
       if (SwiftLanguageRuntime::MethodName::ExtractFunctionBasenameFromMangled(
               mangled, basename, is_method)) {
         if (basename && basename != mangled)
-          return basename);
+          return basename;
       }
     }
   }