xwm: Plug kill signal for killing X apps

Xeyes is the counter-example that fails on that heuristic and won't be caught
on kill binding. This and the last two patches should fix:

    https://bugs.freedesktop.org/show_bug.cgi?id=53679

Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
2 files changed