test if usbmuxd can call statfs on /sys filesystem
    
    Recent testing revealed that the usbmuxd service triggers SELinux
    denials during its start. SELinux prevented the usbmuxd process
    from accessing the /sys filesystem. The TC reproduces the situation.
    
    I believe this access should be allowed in SELinux policy. The TC
    looks for appropriate policy rules.
    
    The TC covers BZ#1930992.