NewSELinuxRunner returns a new SELinuxRunner appropriate for the platform.

SELinuxEnabled returns whether SELinux is enabled on the system.

SetFileLabel applies the SELinux label on the path or returns an error.

Note: the libcontainer SELinux package is only built for Linux, so it is necessary to have a NOP wrapper which is built for non-Linux platforms to allow code that links to this package not to differentiate its own methods for Linux and non-Linux platforms.