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>