util_linux_cgo: restore old behavior
util_linux_cgo: restore old behavior

lxc_abstract_unix_recv_fds() used to return 0 if recvmsg() returned 0
and ret if it return < 0. Let's restore that behavior.

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

lxc/lxd,mjeanson/lxd,stgraber/lxd,atxwebs/lxd,hallyn/lxd,lxc/lxd,atxwebs/lxd,hallyn/lxd,Skarlso/lxd,stgraber/lxd,lxc/lxd,lxc/lxd,lxc/lxd,hallyn/lxd,stgraber/lxd,stgraber/lxd,Skarlso/lxd,Skarlso/lxd,mjeanson/lxd,hallyn/lxd,stgraber/lxd,lxc/lxd,stgraber/lxd,lxc/lxd,hallyn/lxd,mjeanson/lxd,atxwebs/lxd,stgraber/lxd,hallyn/lxd,Skarlso/lxd,atxwebs/lxd