main_notify: define main_task so we can use it for assertions

It'll be easier to keep track of what code runs in what
task/thread this way.

src/main_notify.c

@@ -27,7 +27,7 @@
 
 static struct ioOps main_notify_IO;
 static int main_pipe[2];
-static pthread_t main_task;
+pthread_t main_task;
 static Notify main_notify;
 static pthread_mutex_t select_mutex = PTHREAD_MUTEX_INITIALIZER;
 
@@ -60,6 +60,7 @@ static int ioops_consume(int fd_count, fd_set * rfds,
 
 void init_main_notify(void)
 {
+	main_task = pthread_self();
 	init_async_pipe(main_pipe);
 	main_notify_IO.fdset = ioops_fdset;
 	main_notify_IO.consume = ioops_consume;

src/main_notify.h

@@ -21,6 +21,10 @@
 #ifndef MAIN_NOTIFY_H
 #define MAIN_NOTIFY_H
 
+#include <pthread.h>
+
+extern pthread_t main_task;
+
 void init_main_notify(void);
 
 void deinit_main_notify(void);