'urgent' messages

Follow up on some old groundwork.  For tty, if the core has designated
a message as 'urgent', override any message suppression taking place
because of ESC typed at the --More-- prompt.  Right now, "You die"
messages, feedback about having something stolen, feedback for
"amorous demon" interaction (mainly in case of armor removal), and
exploding a bag of holding are treated as urgent.

The "You die" case is already handled by a hack in top-line handling;
I left that in place so the conversion of 3 or 4 pline("You die.*")
to custompline(URGENT_MESSAGE, "You die.*") was redundant.  There
are probably various non-You_die messages which precede done() which
should be marked urgent too.

Other interfaces might want to do something similar.  And we ought to
implement MSGTYPE=force or MSGTYPE=urgent to allow players to indicate
other messages that they want have to override suppression.  But I'm
not intending to work on either of those.  I mainly wanted to force
the magic bag explosion message to be shown since a sequence of "You
put <foo> into <bag>." messages is a likely candidate for --More--ESC.

src/hack.c

@@ -3252,7 +3252,7 @@ maybe_wail(void)
 }
 
 void
-losehp(register int n, register const char *knam, boolean k_format)
+losehp(int n, const char *knam, boolean k_format)
 {
 #if 0   /* code below is prepared to handle negative 'loss' so don't add this
          * until we've verified that no callers intentionally rely on that */
@@ -3281,7 +3281,7 @@ losehp(register int n, register const char *knam, boolean k_format)
         g.killer.format = k_format;
         if (g.killer.name != knam) /* the thing that killed you */
             Strcpy(g.killer.name, knam ? knam : "");
-        You("die...");
+        custompline(URGENT_MESSAGE, "You die...");
         done(DIED);
     } else if (n > 0 && u.uhp * 10 < u.uhpmax) {
         maybe_wail();