coverity: close fout on error in is_wlan()
coverity: close fout on error in is_wlan()

Signed-off-by: Serge Hallyn <3df611b026e4639bee8aef7a4beb2e39fcebb313@ubuntu.com>

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