change the type of xytod()'s return value to int

xytod()'s return value is an index, so its type should be int, not coordxy.

src/zap.c

@@ -4126,7 +4126,7 @@ boomhit(struct obj *obj, coordxy dx, coordxy dy)
     gb.bhitpos.x = u.ux;
     gb.bhitpos.y = u.uy;
     boom = counterclockwise ? S_boomleft : S_boomright;
-    i = (int) xytod(dx, dy);
+    i = xytod(dx, dy);
     tmp_at(DISP_FLASH, cmap_to_glyph(boom));
     for (ct = 0; ct < 10; ct++) {
         i = DIR_CLAMP(i);