Switch to Enforcers bloody skin when he's killed, fixes #331

When killing the enforcer with one shot (instead of damaging him first
without killing, which will switch to the bloody skin), the skin wasn't
changed. Now it is.

src/game/monster/infantry/infantry.c

@@ -532,6 +532,7 @@ infantry_die(edict_t *self, edict_t *inflictor /* unused */,
 	/* regular death */
 	self->deadflag = DEAD_DEAD;
 	self->takedamage = DAMAGE_YES;
+	self->s.skinnum = 1; /* switch to bloody skin */
 
 	n = randk() % 3;