salomesmesh: fix function missing return statement

3rdParty/salomesmesh/src/SMESHDS/SMESHDS_GroupOnGeom.cpp|95 col 3| warning: control may reach end of non-void function [-Wreturn-type]
||   }

src/3rdParty/salomesmesh/src/SMESHDS/SMESHDS_GroupOnGeom.cpp

@@ -92,6 +92,7 @@ class MyIterator: public SMDS_ElemIterator
       else
         myElem = 0;
     }
+	return res;
   }
 };