cexec should mount sysfs when running commands in chroot

[vilkaspilkas]

Expected Behaviour

Commands requiring sysfs inside the chroot should work.

Current Behaviour

Currently cexec mounts /dev and /proc filesystems inside the chroot before running commands, however there are some commands that also require sysfs presence.

Possible Solution

Add code to mount sysfs in the MountSpecialDirs function.