lxc-busybox.in: check separately that /usr/lib64 exists
lxc-busybox.in: check separately that /usr/lib64 exists

It's possible for only one of /lib64 and /usr/lib64 to exist, so
adding both fstab entries can cause the busybox container to fail
to start.

Signed-off-by: Serge Hallyn <3df611b026e4639bee8aef7a4beb2e39fcebb313@ubuntu.com>
Signed-off-by: Daniel Lezcano <3211518dd4d87cb3f7ee12cb52e14b7fb2bc0446@fr.ibm.com>

lazy404/lxc,aeris/lxc,Ponce/lxc,glensc/lxc,LynxChaus/lxc,smoser/lxc,rldleblanc/lxc,hfuCN/lxc,federicobriata/lxc,efiop/lxc,efiop/lxc,federicobriata/lxc,ecarrara/lxc,aeris/lxc,ojkastl/lxc_Patches,yubo/lxc,federicobriata/lxc,thmo/lxc,jirislaby/lxc,Distrotech/lxc,DarknessBeforeDawn/lxc,ysbnim/lxc,regit/lxc,lisongmin/lxc,hallyn/lxc,rowhit/lxc,lisongmin/lxc,raspberrypython/lxc,weizhenwei/lxc,smoser/lxc,virajs/lxc,rowhit/lxc,Distrotech/lxc,JohnPeacockMessageSystems/lxc,smoser/lxc,coconutpilot/lxc-gentoo-new,armcc/lxc,efiop/lxc,sapun/lxc,ecarrara/lxc,raspberrypython/lxc,ksperis/lxc,GreatFruitOmsk/lxc,QingweiPeterLan/cs188-lxc,bostjan/lxc,major/lxc,major/lxc,caglar10ur/lxc,Pelagicore/lxc,codebauss/lxc,yubo/lxc,bostjan/lxc,weizhenwei/lxc,akshaykarle/lxc,bmoar/lxc,Distrotech/lxc,ss1h2a3tw/lxc,akshaykarle/lxc,szaszg/lxc,christiaan/lxc,caglar10ur/lxc,armcc/lxc,ksperis/lxc,ioops/lxc,rldleblanc/lxc,major/lxc,terceiro/lxc,ioops/lxc,bmoar/lxc,glensc/lxc,jirislaby/lxc,jirislaby/lxc,bmoar/lxc,Pelagicore/lxc,caglar10ur/lxc,terceiro/lxc,ojkastl/lxc_Patches,abstrakraft/lxc-android-lxc,smoser/lxc,hkjolhede/lxc,armcc/lxc,raspberrypython/lxc,QingweiPeterLan/cs188-lxc,ksperis/lxc,lisongmin/lxc,JohnPeacockMessageSystems/lxc,rldleblanc/lxc,DarknessBeforeDawn/lxc,rowhit/lxc,regit/lxc,Ponce/lxc,LynxChaus/lxc,hkjolhede/lxc,tych0/lxc,ysbnim/lxc,JohnPeacockMessageSystems/lxc,hfuCN/lxc,ysbnim/lxc,QingweiPeterLan/cs188-lxc,lazy404/lxc,cjwatson/lxc,tych0/lxc,szaszg/lxc,glensc/lxc,GreatFruitOmsk/lxc,DarknessBeforeDawn/lxc,ss1h2a3tw/lxc,coconutpilot/lxc-gentoo-new,christiaan/lxc,tych0/lxc,abstrakraft/lxc-android-lxc,ojkastl/lxc_Patches,hallyn/lxc,cjwatson/lxc,sapun/lxc,regit/lxc,hallyn/lxc,fwilson42/lxc,abstrakraft/lxc-android-lxc,thmo/lxc,virajs/lxc,aeris/lxc,virajs/lxc,ecarrara/lxc,szaszg/lxc,GreatFruitOmsk/lxc,ss1h2a3tw/lxc,akshaykarle/lxc,bostjan/lxc,weizhenwei/lxc,LynxChaus/lxc,fwilson42/lxc,hfuCN/lxc,terceiro/lxc,Pelagicore/lxc,yubo/lxc,abstrakraft/lxc-android-lxc,fwilson42/lxc,sapun/lxc,hkjolhede/lxc,Ponce/lxc,codebauss/lxc,ioops/lxc,cjwatson/lxc,codebauss/lxc,ojkastl/lxc_Patches,lazy404/lxc,christiaan/lxc,thmo/lxc