utils: fix ppc64le builds
utils: fix ppc64le builds

I suspect that there's a glibc bug on ppc64le. Both clang and gcc a very
unhappy when you return -errno from these functions. Instead, let's return
concrete errno numbers, e.g. -EINVAL.

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

lxc/lxc-pkg-ubuntu,lxc/lxc-pkg-ubuntu,lxc/lxc-pkg-ubuntu