Set the kNotGlobal bit when removing a TF1 from the global list.

This avoids spurrious warning about inconsitent state in the case where multiple thread create (for fitting)
multiple function with the same name and remove them 'concurrently' with AddToGlobalList(false).

hist/hist/src/TF1.cxx

@@ -629,6 +629,9 @@ void TF1::DoInitialize(EAddToList addToGlobalList)
       // Store formula in linked list of formula in ROOT
       TF1 *f1old = (TF1 *)gROOT->GetListOfFunctions()->FindObject(fName);
       gROOT->GetListOfFunctions()->Remove(f1old);
+      // We removed f1old from the list, it is not longer global.
+      // (See TF1::AddToGlobalList which requires this flag to be correct).
+      f1old->SetBit(kNotGlobal, kTRUE);
       gROOT->GetListOfFunctions()->Add(this);
    } else
       SetBit(kNotGlobal, kTRUE);
@@ -671,7 +674,7 @@ Bool_t TF1::AddToGlobalList(Bool_t on)
       }
       // do I need to delete previous one with the same name ???
       //TF1 * old = dynamic_cast<TF1*>( gROOT->GetListOfFunctions()->FindObject(GetName()) );
-      //if (old) gROOT->GetListOfFunctions()->Remove(old);
+      //if (old) { gROOT->GetListOfFunctions()->Remove(old); old->SetBit(kNotGlobal, kTRUE); }
       R__LOCKGUARD2(gROOTMutex);
       gROOT->GetListOfFunctions()->Add(this);
       SetBit(kNotGlobal, kFALSE);