fix ipv6 acast / mcast restriction
fix ipv6 acast / mcast restriction

Pointer comparison is buggy as they are never null.
For an ipv6 address configuration, we always zeroed the structure,
hence the bcast and acast structure are equal to in6addr_any.

Any change of this value means the user specified something different
in the configuration file, so we fail gracefully.

Signed-off-by: Daniel Lezcano <3211518dd4d87cb3f7ee12cb52e14b7fb2bc0446@fr.ibm.com>

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