disallow SIOCATMARK

The use of SIOCATMARK is not recommended per rfc6093.

This ioctl is not currently allowed on Android. Add a neverallowxperm
statement (compile time assertion + CTS test) to ensure this never
regresses.

Bug: 68014825
Test: policy compiles.
Change-Id: I41272a0cb157ac9aa38c8e67aabb8385403815f9