MFC pfctl fix (parse.y 1.641, pfctl_parser.c 1.300, pfctl_parser.h 1.104)
-----
Fixup incorrect expansion of the networking mask for dynamic interface
specifications under certain circumstances resulting in potentially
elevated access permissions for IPv6 traffic.  Reported by sthen@;
ok henning benno sthen
-----

Imported to Bitrig by patrick@. ok drahn@