input/curl: fix EventLoop stall after curl_easy_pause

When playing finite http streams, e.g. something from soundcloud,
eventloop stalls after pausing writefunc. TimeoutMonitor is cancelled
by the time resume happens, so when enough data is consumed writefunc
is called only once. Calling InvalidateSockets() from
input_curl_resume() seems to fix the issue.

src/input/CurlInputPlugin.cxx

@@ -245,6 +245,7 @@ input_curl_resume(struct input_curl *c)
 	if (c->paused) {
 		c->paused = false;
 		curl_easy_pause(c->easy, CURLPAUSE_CONT);
+		curl.sockets->InvalidateSockets();
 	}
 }