sim: mn10300: tweak engine halt hook

The hook is a void func, so defining it to 0 triggers warnings,
and isn't really needed.
diff --git a/sim/mn10300/ChangeLog b/sim/mn10300/ChangeLog
index a813e4e..1fd873b 100644
--- a/sim/mn10300/ChangeLog
+++ b/sim/mn10300/ChangeLog
@@ -1,3 +1,7 @@
+2021-06-09  Mike Frysinger  <vapier@gentoo.org>
+
+	* sim-main.h (SIM_ENGINE_HALT_HOOK): Delete 0.
+
 2021-06-08  Mike Frysinger  <vapier@gentoo.org>
 
 	* Makefile.in: Replace $(IGEN) with $(IGEN_RUN) and ../igen/igen
diff --git a/sim/mn10300/sim-main.h b/sim/mn10300/sim-main.h
index e184613..8750729 100644
--- a/sim/mn10300/sim-main.h
+++ b/sim/mn10300/sim-main.h
@@ -22,7 +22,7 @@
 #ifndef SIM_MAIN_H
 #define SIM_MAIN_H
 
-#define SIM_ENGINE_HALT_HOOK(SD,LAST_CPU,CIA) 0 /* disable this hook */
+#define SIM_ENGINE_HALT_HOOK(SD,LAST_CPU,CIA) /* disable this hook */
 
 #include "sim-basics.h"
 #include "sim-signal.h"