bones while swallowed

Michael pointed out that bones will never occur while swallowed because
makemon of the ghost will always fail.  I suggested that the outcome made
sense, since your body may be digested, torn apart, whatever.  But, there
was no explicit check for this to make it obvious this was occuring.

src/bones.c

@@ -165,6 +165,9 @@ can_make_bones()
 	    return FALSE;
 	if (no_bones_level(&u.uz))
 	    return FALSE;		/* no bones for specific levels */
+	if (u.uswallow) {
+	    return FALSE;		/* no bones when swallowed */
+	}
 	if (!Is_branchlev(&u.uz)) {
 	    /* no bones on non-branches with portals */
 	    for(ttmp = ftrap; ttmp; ttmp = ttmp->ntrap)