RootUtils: fix for TSMethodCall destructor

Do not cleanup the thread-specific `TMethodCall` pointer either in case
gCling has already been destroyed.

Control/RootUtils/src/TSMethodCall.cxx

@@ -75,6 +75,7 @@ TSMethodCall::~TSMethodCall()
   TInterpreter* cling ATLAS_THREAD_SAFE = gCling;
   if (!cling) {
     m_meth.release();
+    m_tsMeth.release();
   }
 }