Merge #16405: fix: tor: Call event_base_loopbreak from the event's callback

a981e74 fix: tor: Call event_base_loopbreak from the event's callback (João Barbosa)

Pull request description:

  Calling `event_base_loopbreak` before `event_base_dispatch` has no effect. Fix this by calling `event_base_loopbreak` from the event's callback. From the [documentation](http://www.wangafu.net/~nickm/libevent-2.0/doxygen/html/event_8h.html#a07a7599e478e4031fa8cf52e26d8aa1e):

  > event_base_loop() will abort the loop after the next event is completed; event_base_loopbreak() is typically invoked from this event's callback. This behavior is analogous to the "break;" statement.

  This can be tested by running the following with and without this change:
  ```sh
  bitcoind -- -regtest -proxy=127.0.0.1:9050 -listen=1 -bind=127.0.0.1 -whitebind=127.0.0.1:0
  ```

  Fixes #16376.

ACKs for top commit:
  laanwj:
    code review ACK a981e74
  fanquake:
    ACK a981e74

Tree-SHA512: 328fe71366404d5be8177d7081d5b4868cee73412df631a1865d24fb1c153427210762738109e06b737f037f4c68966812fba041831bb9e8129861f19ce61a63

Author: laanwj

src/torcontrol.cpp

@@ -759,7 +759,9 @@ void InterruptTorControl()
 {
     if (gBase) {
         LogPrintf("tor: Thread interrupt\n");
-        event_base_loopbreak(gBase);
+        event_base_once(gBase, -1, EV_TIMEOUT, [](evutil_socket_t, short, void*) {
+            event_base_loopbreak(gBase);
+        }, nullptr, nullptr);
     }
 }