sandbox: make test not fail on systems without SELinux

On systems without SELinux (eg. some continuous integration
environments), "make test" fails with:

    Traceback (most recent call last):
      File "test_sandbox.py", line 110, in <module>
        if selinux.security_getenforce() == 1:
    FileNotFoundError: [Errno 2] No such file or directory

This is exception is thrown because the selinuxfs file system is not
mounted.

Detect such configurations using selinux.is_selinux_enabled() and skip
the test when SELinux is disabled accordingly.

Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>
1 file changed