e_policy: force render for uniconified client having unused shm buffer

e_policy: force render for uniconified client having unused shm buffer

 If there are clients not supporting iconify state change events, those
clients can request wl_surface@commit anytime after being iconfied. but
wl_surface@commit for iconified clients having shm buffer doesn't affect to
its comp object rendering because the comp object is invisible.
 And even if the client is uniconified, it can be never composited if the client
doesn't send new wl_surface@attach.
 So, wl_callback@done is never sent to client as well, and it's possible to
cause block of client-side rendering.

 To resolve the problem, we need to do force render for uniconified client
having unused shm buffer.

Change-Id: I9d227c3a27b5cdaa1b773a174e772f01ed338886
Signed-off-by: MinJeong Kim <minjjj.kim@samsung.com>