tools: exit with return code of lxc_execute()
tools: exit with return code of lxc_execute()

Signed-off-by: Christian Brauner <48455ab3070520a2d174545c7239d6d0fabd9a83@ubuntu.com>

ss1h2a3tw/lxc,LynxChaus/lxc,terceiro/lxc,hallyn/lxc,GreatFruitOmsk/lxc,caglar10ur/lxc,caglar10ur/lxc,thmo/lxc,GreatFruitOmsk/lxc,caglar10ur/lxc,thmo/lxc,federicobriata/lxc,aeris/lxc,hallyn/lxc,terceiro/lxc,GreatFruitOmsk/lxc,ss1h2a3tw/lxc,federicobriata/lxc,LynxChaus/lxc,terceiro/lxc,thmo/lxc,hallyn/lxc,federicobriata/lxc,LynxChaus/lxc,ss1h2a3tw/lxc,aeris/lxc,aeris/lxc