util linux: guess size when sysconf() returns -1
util linux: guess size when sysconf() returns -1

Signed-off-by: Jason Travis <edd51ceff19ae47ac43f5213eadc13a2adf78343@nau.edu>

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