[Metadata/TypeByName] Don't try to check for dot syntax in presence of symbolic references

If symbolic references are present in the mangled name don't try
to check for convenience dot syntax as well since they can't appear
together.

Author: xedin

stdlib/public/runtime/MetadataLookup.cpp

@@ -851,7 +851,7 @@ swift::_getTypeByMangledName(StringRef typeName,
       return llvm::StringRef::npos;
     if (typeName.find('.', dotPos + 1) != llvm::StringRef::npos)
       return llvm::StringRef::npos;
-    if (typeName.find('$') != llvm::StringRef::npos)
+    if (typeName.find('\1') != llvm::StringRef::npos)
       return llvm::StringRef::npos;
     return dotPos;
   };