Fix arm64 build
Fix arm64 build

dup2 doesn't exist on arm64, we've got to use dup3 instead.

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

hallyn/lxd,atxwebs/lxd,Skarlso/lxd,lxc/lxd,yura-pakhuchiy/lxd,jsavikko/lxd,techtonik/lxd,techtonik/lxd,stgraber/lxd,yura-pakhuchiy/lxd,lxc/lxd,pcdummy/lxd,hallyn/lxd,jsavikko/lxd,dustinkirkland/lxd,Skarlso/lxd,dustinkirkland/lxd,lxc/lxd,chrisglass/lxd,mjeanson/lxd,stgraber/lxd,atxwebs/lxd,atxwebs/lxd,georghopp/lxd,hallyn/lxd,erikmack/lxd,georghopp/lxd,pcdummy/lxd,atxwebs/lxd,techtonik/lxd,jsavikko/lxd,mjeanson/lxd,hallyn/lxd,pcdummy/lxd,chrisglass/lxd,stgraber/lxd,akshaykarle/lxd,dustinkirkland/lxd,stgraber/lxd,akshaykarle/lxd,ollie314/lxd,hallyn/lxd,stgraber/lxd,Skarlso/lxd,mjeanson/lxd,ollie314/lxd,yura-pakhuchiy/lxd,chrisglass/lxd,lxc/lxd,lxc/lxd,stgraber/lxd,erikmack/lxd,erikmack/lxd,lxc/lxd,georghopp/lxd,lxc/lxd,akshaykarle/lxd,ollie314/lxd,hallyn/lxd,Skarlso/lxd,stgraber/lxd