lxc-checkconfig: remove zgrep dependency
lxc-checkconfig: remove zgrep dependency

zgrep is a script provided by the 'gzip' package, which may not be
installed on embedded systems etc which use busybox instead of the
standard full-featured utilities.

Signed-off-by: Andre McCurdy <8f09cea6116be1c651ee99f9f5914cb35309ce01@gmail.com>

QingweiPeterLan/cs188-lxc,aeris/lxc,cjwatson/lxc,bostjan/lxc,tych0/lxc,terceiro/lxc,ysbnim/lxc,armcc/lxc,GreatFruitOmsk/lxc,caglar10ur/lxc,ss1h2a3tw/lxc,hfuCN/lxc,federicobriata/lxc,akshaykarle/lxc,hallyn/lxc,Distrotech/lxc,GreatFruitOmsk/lxc,GreatFruitOmsk/lxc,Distrotech/lxc,armcc/lxc,Distrotech/lxc,hfuCN/lxc,ysbnim/lxc,LynxChaus/lxc,terceiro/lxc,caglar10ur/lxc,bostjan/lxc,LynxChaus/lxc,federicobriata/lxc,ss1h2a3tw/lxc,aeris/lxc,cjwatson/lxc,cjwatson/lxc,caglar10ur/lxc,hfuCN/lxc,terceiro/lxc,hallyn/lxc,QingweiPeterLan/cs188-lxc,akshaykarle/lxc,tych0/lxc,thmo/lxc,bostjan/lxc,tych0/lxc,aeris/lxc,ysbnim/lxc,ss1h2a3tw/lxc,akshaykarle/lxc,thmo/lxc,thmo/lxc,federicobriata/lxc,armcc/lxc,LynxChaus/lxc,QingweiPeterLan/cs188-lxc,hallyn/lxc