grateful frozen monsters

a frozen (possibly sleeping) monster cannot be grateful unless it wakes up.
From a bug report.  The pit case can only happen if mfrozen is
non-zero, but other traps may leave msleeping set as well.

src/trap.c

@@ -2886,6 +2886,7 @@ struct monst *mtmp;
 {
 	if (!ttmp->madeby_u) {
 	    if (rnl(10) < 8 && !mtmp->mpeaceful &&
+		    !mtmp->msleeping && !mtmp->mfrozen &&
 		    !mindless(mtmp->data) &&
 		    mtmp->data->mlet != S_HUMAN) {
 		mtmp->mpeaceful = 1;