7123954: Some CTW test crash with SIGSEGV

Correct Allocate expansion code to preserve i_o when only slow call is generated.

Reviewed-by: iveresov

hotspot/src/share/vm/opto/compile.cpp

@@ -2522,7 +2522,7 @@ static void final_graph_reshaping_impl( Node *n, Final_Reshape_Counts &frc ) {
             break;
           }
         }
-        assert(p != NULL, "must be found");
+        assert(proj != NULL, "must be found");
         p->subsume_by(proj);
       }
     }