Define RemoveGeoManager weakly.

Hopefully allows those with RemoveGeoManager function define
to run. and those without to not worry about it.

macro/run/run_reco.C

@@ -95,6 +95,8 @@
  ** from the ROOT prompt without user intervention.
  **
  **/
+void RemoveGeoManager() __attribute__((weak)); 
+
 void run_reco(TString input = "", Int_t nTimeSlices = -1, Int_t firstTimeSlice = 0, TString output = "",
               TString sEvBuildRaw = "", TString setup = "sis100_electron", TString paramFile = "",
               Bool_t debugWithMC = false)
@@ -579,7 +581,7 @@ void run_reco(TString input = "", Int_t nTimeSlices = -1, Int_t firstTimeSlice =
 
   // -----   This is to prevent a malloc error when exiting ROOT   ----------
   // The source of the error is unknown. Related to TGeoManager.
-  RemoveGeoManager();
+  if (RemoveGeoManager) RemoveGeoManager();
   // ------------------------------------------------------------------------
 
 }  // End of main macro function