conf: do not use %m format specifier
conf: do not use %m format specifier

This is a GNU extension and some libcs might be missing it.

Signed-off-by: Christian Brauner <48455ab3070520a2d174545c7239d6d0fabd9a83@canonical.com>

thmo/lxc,GreatFruitOmsk/lxc,ss1h2a3tw/lxc,aeris/lxc,terceiro/lxc,terceiro/lxc,hallyn/lxc,federicobriata/lxc,thmo/lxc,hallyn/lxc,caglar10ur/lxc,ysbnim/lxc,hfuCN/lxc,LynxChaus/lxc,cjwatson/lxc,aeris/lxc,caglar10ur/lxc,cjwatson/lxc,ss1h2a3tw/lxc,GreatFruitOmsk/lxc,ysbnim/lxc,hfuCN/lxc,LynxChaus/lxc,GreatFruitOmsk/lxc,ysbnim/lxc,federicobriata/lxc,cjwatson/lxc,LynxChaus/lxc,hallyn/lxc,caglar10ur/lxc,federicobriata/lxc,aeris/lxc,ss1h2a3tw/lxc,terceiro/lxc,thmo/lxc,hfuCN/lxc