Redmine #2693: some 10_files tests check for unpromised gid numbers

Some platforms, such as HP-UX, do not have root in group 0 by default.
Certain tests expect a string showing mode, nlinks, uid, gid, and size
to show a uid and gid of zero for the test file, but without promising
the GID the file defaults to root's primary group. On HP-UX this is 3,
causing the test to fail.

The tests have been updated to promise the same mode, uid, and gid that
are expected in the "expect" string for the test file that is created.