fake player creation on Astral

Reported by entrez:  fake player monsters on the Astral Plane level
were giving "<role> suddenly appears!" feedback if they could be
seen or sensed when the hero arrived on that level.

They're generated separately from the level itself so the message
suppression in place during level creation didn't guard against it.

src/mplayer.c

@@ -128,7 +128,7 @@ mk_mplayer(struct permonst *ptr, coordxy x, coordxy y, boolean special)
     if (!In_endgame(&u.uz))
         special = FALSE;
 
-    if ((mtmp = makemon(ptr, x, y, NO_MM_FLAGS)) != 0) {
+    if ((mtmp = makemon(ptr, x, y, special ? MM_NOMSG : NO_MM_FLAGS)) != 0) {
         short weapon, armor, cloak, helm, shield;
         int quan;
         struct obj *otmp;