Show track count in library tree while add/update is in progress

This is just to give a sense of progress now that the default status
line no longer shows the library duration. It felt a bit bloated to
print it all the time though.

(And fix typo in an existing check.)

ui_curses.c

@@ -965,7 +965,13 @@ static void update_window(struct window *win, int x, int y, int w, const char *t
 
 static void update_tree_window(void)
 {
-	update_window(lib_tree_win, tree_win_x, 0, tree_win_w + 1, "Library", print_tree);
+	static GBUF(buf);
+	gbuf_clear(&buf);
+
+	gbuf_add_str(&buf, "Library");
+	if (worker_has_job())
+		gbuf_addf(&buf, " - %d tracks", lib_editable.nr_tracks);
+	update_window(lib_tree_win, tree_win_x, 0, tree_win_w + 1, buf.buffer, print_tree);
 }
 
 static void update_track_window(void)

worker.c

@@ -187,6 +187,12 @@ void worker_remove_jobs_by_cb(worker_match_cb cb, void *opaque)
 	worker_unlock();
 }
 
+int worker_has_job(void)
+{
+	/* lock not needed for this simple check */
+	return cur_job || !list_empty(&worker_job_head);
+}
+
 int worker_has_job_by_type(uint32_t pat)
 {
 	return worker_has_job_by_cb(worker_matches_type, &pat);
@@ -204,7 +210,7 @@ int worker_has_job_by_cb(worker_match_cb cb, void *opaque)
 			break;
 		}
 	}
-	if (cur_job && cb(job->type, job->data, opaque))
+	if (cur_job && cb(cur_job->type, cur_job->data, opaque))
 		has_job = 1;
 	worker_unlock();
 	return has_job;

worker.h

@@ -40,6 +40,7 @@ void worker_add_job(uint32_t type, void (*job_cb)(void *job_data),
 void worker_remove_jobs_by_type(uint32_t pat);
 void worker_remove_jobs_by_cb(worker_match_cb cb, void *opaque);
 
+int worker_has_job(void);
 int worker_has_job_by_type(uint32_t pat);
 int worker_has_job_by_cb(worker_match_cb cb, void *opaque);