Always run async signal handlers in the main UI

Async signal handlers have no connection to whichever was the current
UI, and thus always run on the main one.

gdb/ChangeLog:
2016-06-21  Pedro Alves  <palves@redhat.com>

	* event-loop.c: Include top.h.
	(invoke_async_signal_handlers): Switch to the main UI.
	* event-top.c (main_ui_): Update comment.
	(main_ui): New global.
	* top.h (main_ui): Declare.

1 files changed, 5 insertions, 0 deletions

diff --git a/gdb/top.h b/gdb/top.h
index 80fcb40..a76abaf 100644
--- a/gdb/top.h
+++ b/gdb/top.h
@@ -86,6 +86,11 @@ struct ui
   struct ui_file *m_gdb_stdlog;
 };
 
+/* The main UI.  This is the UI that is bound to stdin/stdout/stderr.
+   It always exists and is created automatically when GDB starts
+   up.  */
+extern struct ui *main_ui;
+
 /* The current UI.  */
 extern struct ui *current_ui;