Fix a possible hang in dig if a send is interrupted/canceled

When send_done() is called with a ISC_R_CANCELED status (e.g. because
of a signal from ctrl+c), dig can fail to shutdown because
check_if_done() is not called in the branch. Add a check_if_done()
call.

(cherry picked from commit 5d1a8fe755)

bin/dig/dighost.c

@@ -2754,6 +2754,7 @@ send_done(isc_nmhandle_t *handle, isc_result_t eresult, void *arg) {
 		}
 		query_detach(&query);
 		lookup_detach(&l);
+		check_if_done();
 		return;
 	} else if (eresult != ISC_R_SUCCESS) {
 		debug("send failed: %s", isc_result_totext(eresult));