Provide jack2 compatible implementation for jack1

jack1 (which is Linux only) does not have a jack_client_stop_thread
API, and expects the application to call pthread_join().

This fixes an issue when the application is compiled using jack2 headers
but the application later runs using jack1's library.

libs/backends/jack/weak_libjack.def

@@ -138,7 +138,12 @@ JCFUN(0, int,            client_real_time_priority, 0)
 JCFUN(0, int,            client_max_real_time_priority, 0)
 JPFUN(0, int,            acquire_real_time_scheduling, (jack_native_thread_t t, int p), (t,p), 0)
 JPFUN(0, int,            drop_real_time_scheduling, (jack_native_thread_t t), (t), 0)
+#if (!defined _WIN32 && (defined _REENTRANT || defined __linux__))
+	/* on POSIX systems, call pthread_join() when libjack does not provide jack_client_stop_thread */
+JXFUN(0, int,            client_stop_thread, (jack_client_t* c, jack_native_thread_t t), (c,t), if (t) { pthread_join(t, NULL); return 0; } else { return -1;})
+#else
 JPFUN(0, int,            client_stop_thread, (jack_client_t* c, jack_native_thread_t t), (c,t), 0)
+#endif
 JPFUN(0, int,            client_kill_thread, (jack_client_t* c, jack_native_thread_t t), (c,t), 0)
 #ifndef _WIN32
 JVFUN(0,                 set_thread_creator, (jack_thread_creator_t c), (c),)