misccoms.c, exit immediately, if not shared ngspice,

do exit only after cleaning all memory if 'set ngdebug' is given.

src/frontend/misccoms.c

@@ -56,6 +56,11 @@ com_quit(wordlist *wl)
         if (!noask && !confirm_quit())
             return;
 
+#ifndef SHARED_MODULE
+	if (!ft_ngdebug)
+	    exit(exitcode);
+#endif
+
     /* start to clean up the mess */
 
 #ifdef SHARED_MODULE