t/t1304: set the Default ACL base entries

t/t1304: set the Default ACL base entries

According to the Linux setfacl man page, in order for an ACL to be valid,
the following rules must be satisfied:

   * Whenever an ACL contains any Default ACL entries, the three Default
     ACL base entries (default owner, default group, and default others)
     must also exist.

   * Whenever a Default ACL contains named user entries or named group
     objects, it must also contain a default effective rights mask.

Some implementations of setfacl (Linux) do this automatically when
necessary, some (Solaris) do not.  Solaris's setfacl croaks when trying to
create a default user ACL if the above rules are not satisfied.  So, create
them before modifying the default user ACL's.

Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil>
Signed-off-by: Junio C Hamano <gitster@pobox.com>