Merge pull request #4259 from shuujii/use-eException_class-instead-of-mrb_class_get

Use `mrb->eException_class` instead of `mrb_class_get()`

mrbgems/mruby-bin-debugger/tools/mrdb/cmdmisc.c

@@ -495,7 +495,7 @@ dbgcmd_quit(mrb_state *mrb, mrdb_state *mrdb)
 
   if (mrdb->dbg->xm == DBG_QUIT) {
     struct RClass *exc;
-    exc = mrb_define_class(mrb, "DebuggerExit", mrb_class_get(mrb, "Exception"));
+    exc = mrb_define_class(mrb, "DebuggerExit", mrb->eException_class);
     mrb_raise(mrb, exc, "Exit mrdb.");
   }
   return DBGST_PROMPT;

mrbgems/mruby-bin-debugger/tools/mrdb/cmdrun.c

@@ -19,7 +19,7 @@ dbgcmd_run(mrb_state *mrb, mrdb_state *mrdb)
     if (dbg->xphase == DBG_PHASE_RUNNING){
       struct RClass *exc;
       puts("Start it from the beginning.");
-      exc = mrb_define_class(mrb, "DebuggerRestart", mrb_class_get(mrb, "Exception"));
+      exc = mrb_define_class(mrb, "DebuggerRestart", mrb->eException_class);
       mrb_raise(mrb, exc, "Restart mrdb.");
     }
   }