xwm: Fix input regions

commit 0f99e081 broke xwayland client
input regions. The xwayland window manager sets input regions in the
pending state without going through the function that sets the
WESTON_SURFACE_DIRTY_INPUT bit.

Just add the dirty bit to the xwm code.

Also, fix the whitespace error the same patch introduced.

fixes 0f99e081

Signed-off-by: Derek Foreman <derek.foreman@collabora.com>