timeout: Add function for deinit system timers

Picked from espressif/esp-lwip@2749568f
Ref IDF-4847

src/core/timeouts.c

@@ -272,6 +272,15 @@ void sys_timeouts_init(void)
   }
 }
 
+/** Deinitialize this module */
+void sys_timeouts_deinit(void)
+{
+  size_t i;
+  /* tcp_tmr() at index 0 is started on demand */
+  for (i = (LWIP_TCP ? 1 : 0); i < LWIP_ARRAYSIZE(lwip_cyclic_timers); i++) {
+    sys_untimeout(lwip_cyclic_timer, LWIP_CONST_CAST(void *, &lwip_cyclic_timers[i]));
+  }
+}
 /**
  * Create a one-shot timer (aka timeout). Timeouts are processed in the
  * following cases:

src/include/lwip/timeouts.h

@@ -101,6 +101,7 @@ struct sys_timeo {
 };
 
 void sys_timeouts_init(void);
+void sys_timeouts_deinit(void);
 
 #if LWIP_DEBUG_TIMERNAMES
 void sys_timeout_debug(u32_t msecs, sys_timeout_handler handler, void *arg, const char* handler_name);