djinn/ghosts from potions

<Someone> wrote:
>It seems silly to have two flags being used for counting djinn and
>ghosts, now that there's mvitals.born...

This does not break save and bones compatibility in the 3.4.x branch,
it changes the code, but leaves the obsolete fields in flags.

include/context.h

@@ -80,7 +80,6 @@ struct context_info {
 				/* 8: travel */
 	unsigned startingpet_mid;
 	int	 warnlevel;
-	int	 djinni_count, ghost_count;	/* potion effect tuning */
 	long next_attrib_check;	/* next attribute check */
 	long stethoscope_move;
 	short stethoscope_movement;