vomiting while fainting

From a beta-tester running 3.6.0:
|You faint from lack of food.
|You suddenly vomit!

The latter has already been changed to "You vomit" (it's given at the
end of a multiple-message vomiting countdown so wasn't "sudden") but is
still odd if your stomach is so empty that you're subject to fainting.
Give an alternate message in that case:
|Your stomach heaves convulsively!

Vomiting while unconscious (when that's due to something other than
fainting from hunger) should pose a risk of choking to death, but I'm
going to pretend that this hasn't occurred to me....

src/eat.c

@@ -3154,12 +3154,18 @@ skipfloor:
 void
 vomit() /* A good idea from David Neves */
 {
-    if (cantvomit(youmonst.data))
+    if (cantvomit(youmonst.data)) {
         /* doesn't cure food poisoning; message assumes that we aren't
            dealing with some esoteric body_part() */
         Your("jaw gapes convulsively.");
-    else
+    } else {
         make_sick(0L, (char *) 0, TRUE, SICK_VOMITABLE);
+        /* if not enough in stomach to actually vomit then dry heave;
+           vomiting_dialog() gives a vomit message when its countdown
+           reaches 0, but only if u.uhs < FAINTING (and !cantvomit()) */
+        if (u.uhs >= FAINTING)
+            Your("%s heaves convulsively!", body_part(STOMACH));
+    }
 
     /* nomul()/You_can_move_again used to be unconditional, which was
        viable while eating but not for Vomiting countdown where hero might