core: delay focus updates

Delay focus updates until critical section. Rational is that focus
events might arrive when the focused window hasn't been managed by
compton, result in that that window not being focused.

This commit makes compton mark focus update events, and only update
focus in critical section, after we managed all the new windows.

Fixes #177

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/compton.h

@@ -42,15 +42,11 @@ uint32_t determine_evmask(session_t *ps, xcb_window_t wid, win_evmode_t mode);
 
 xcb_window_t find_client_win(session_t *ps, xcb_window_t w);
 
-void recheck_focus(session_t *ps);
-
 /// Handle configure event of a root window
 void configure_root(session_t *ps, int width, int height);
 
 void circulate_win(session_t *ps, xcb_circulate_notify_event_t *ce);
 
-void update_ewmh_active_win(session_t *ps);
-
 void update_refresh_rate(session_t *ps);
 
 void root_damaged(session_t *ps);