exec: kill forkexec on abnormal websocket closure
exec: kill forkexec on abnormal websocket closure

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

lxc/lxd,stgraber/lxd,Skarlso/lxd,pcdummy/lxd,stgraber/lxd,georghopp/lxd,techtonik/lxd,techtonik/lxd,mjeanson/lxd,lxc/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,hallyn/lxd,lxc/lxd,stgraber/lxd,Skarlso/lxd,stgraber/lxd,hallyn/lxd,atxwebs/lxd,erikmack/lxd,mjeanson/lxd,Skarlso/lxd,jsavikko/lxd,pcdummy/lxd,techtonik/lxd,hallyn/lxd,hallyn/lxd,lxc/lxd,lxc/lxd,erikmack/lxd,mjeanson/lxd,georghopp/lxd,hallyn/lxd,pcdummy/lxd,atxwebs/lxd,atxwebs/lxd,erikmack/lxd,jsavikko/lxd,stgraber/lxd,hallyn/lxd,atxwebs/lxd,lxc/lxd,georghopp/lxd,Skarlso/lxd,jsavikko/lxd