is a non-portable call that returns the ACL brand for the ACL
Upon successful completion, the location referred to by the argument
will be set to the ACL brand of the ACL
Branding is an internal mechanism intended to prevent mixing POSIX.1e
and NFSv4 entries by mistake.
It's also used by the libc to determine how to print out the ACL.
The first call to function that is specific for one particular brand - POSIX.1e
or NFSv4 - "brands" the ACL.
After that, calling function specific to another brand will result in error.