fix: try to fix segfault at 240 steps by adding WithShell guard for writecheck_sh call

AMSS_NCKU_source/bssn_gpu_class.C

@@ -2134,7 +2134,9 @@ void bssn_class::Evolve(int Steps)
 
       CheckPoint->write_Black_Hole_position(BH_num_input, BH_num, Porg0, Porgbr, Mass);
       CheckPoint->writecheck_cgh(PhysTime, GH);
+#ifdef WithShell
       CheckPoint->writecheck_sh(PhysTime, SH);
+#endif
       CheckPoint->write_bssn(LastDump, Last2dDump, LastAnas);
     }
   }