pthread_cancel() is not available on Android

Thus mosquitto_loop_start() and mosquitto_loop_stop()
won't be available there (and mosquitto_connect_async()
as a consequence).

Signed-off-by: Daniel d'Andrada <daniel.dandrada@esrlabs.com>

config.h

@@ -61,4 +61,9 @@
 
 #define UNUSED(A) (void)(A)
 
+/* Android Bionic libpthread implementation doesn't have pthread_cancel */
+#ifndef ANDROID
+#  define HAVE_PTHREAD_CANCEL
+#endif
+
 #endif

lib/mosquitto.c

@@ -201,11 +201,13 @@ void mosquitto__destroy(struct mosquitto *mosq)
 	if(!mosq) return;
 
 #ifdef WITH_THREADING
+#  ifdef HAVE_PTHREAD_CANCEL
 	if(mosq->threaded == mosq_ts_self && !pthread_equal(mosq->thread_id, pthread_self())){
 		pthread_cancel(mosq->thread_id);
 		pthread_join(mosq->thread_id, NULL);
 		mosq->threaded = mosq_ts_none;
 	}
+#  endif
 
 	if(mosq->id){
 		/* If mosq->id is not NULL then the client has already been initialised

lib/thread_mosq.c

@@ -27,7 +27,7 @@ void *mosquitto__thread_main(void *obj);
 
 int mosquitto_loop_start(struct mosquitto *mosq)
 {
-#ifdef WITH_THREADING
+#if defined(WITH_THREADING) && defined(HAVE_PTHREAD_CANCEL)
 	if(!mosq || mosq->threaded != mosq_ts_none) return MOSQ_ERR_INVAL;
 
 	mosq->threaded = mosq_ts_self;
@@ -43,7 +43,7 @@ int mosquitto_loop_start(struct mosquitto *mosq)
 
 int mosquitto_loop_stop(struct mosquitto *mosq, bool force)
 {
-#ifdef WITH_THREADING
+#if defined(WITH_THREADING) && defined(HAVE_PTHREAD_CANCEL)
 #  ifndef WITH_BROKER
 	char sockpair_data = 0;
 #  endif