fix memory leaks reported by cppcheck in src/lxc/lxc_usernsexec.c
fix memory leaks reported by cppcheck in src/lxc/lxc_usernsexec.c

Free previously allocated memory if realloc fails.

Signed-off-by: S.Çağlar Onur <acf5ae661bb0a9f738c88a741b1d35ac69ab5408@10ur.org>
Signed-off-by: Serge Hallyn <3df611b026e4639bee8aef7a4beb2e39fcebb313@ubuntu.com>

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