[Minor] Explicit specify order of binary operations

../contrib/libev/ev.c: In function ‘ev_io_start’:
../contrib/libev/ev.c:4396:34: warning: suggest parentheses around arithmetic in operand of ‘|’ [-Wparentheses]
 4396 |   fd_change (EV_A_ fd, w->events & EV__IOFDSET | EV_ANFD_REIFY);
      |                        ~~~~~~~~~~^~~~~~~~~~~~~

contrib/libev/ev.c

@@ -4388,7 +4388,7 @@ ev_io_start (EV_P_ ev_io *w) EV_NOEXCEPT
   /* common bug, apparently */
   assert (("libev: ev_io_start called with corrupted watcher", ((WL)w)->next != (WL)w));
 
-  fd_change (EV_A_ fd, w->events & EV__IOFDSET | EV_ANFD_REIFY);
+  fd_change (EV_A_ fd, (w->events & EV__IOFDSET) | EV_ANFD_REIFY);
   w->events &= ~EV__IOFDSET;
 
   EV_FREQUENT_CHECK;