Silence g_util.c warning about set but not read variable

Probably caused by my commit on June 2 2017.

  commit 4006358
  Fix spawn/freed entity logic (specifically harvester skulls)

code/game/g_utils.c

@@ -391,7 +391,6 @@ gentity_t *G_Spawn( void ) {
 	gentity_t	*e;
 
 	e = NULL;	// shut up warning
-	i = 0;		// shut up warning
 	for ( force = 0 ; force < 2 ; force++ ) {
 		// if we go through all entities and can't find one to free,
 		// override the normal minimum times before use