Merge pull request #37196 from bnbarham/warn-on-invalid-sourceinfo

[Serialization] Add warning when .swiftsourceinfo is malformed

lib/Serialization/ModuleFileSharedCore.cpp

@@ -1496,3 +1496,7 @@ ModuleFileSharedCore::ModuleFileSharedCore(
     return;
   }
 }
+
+bool ModuleFileSharedCore::hasSourceInfo() const {
+  return !!DeclUSRsTable;
+}