libweston/input.c: Fix weston crash with the mouse event

Fix weston crash when user click the mouse continuosly while
the video is playing.
Call weston_view_update_transform before calling
weston_coord_global_to_surface to update view->transform.dirty to 0.

Fixes #985

Tested-by: Sooyeon Kang <sooyeon8979@gmail.com>
Signed-off-by: Sooyeon Kang <sooyeon8979@gmail.com>