client: Fix ConnectLXDUnix regression
client: Fix ConnectLXDUnix regression

For some reason some logic actively relies on unixPath being empty if it was
provided that way by the user.

Signed-off-by: Stéphane Graber <089afc6d81f66f1168a9849e15660feae286e024@ubuntu.com>

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