Aaron Liu authored Jan 31, 2022 and Brad King committed Jan 31, 2022

The TestFileAccess test fails on AIX with this message:

    TestFileAccess incorrectly indicated that this is a writable file

If the test is run as root, skip that part of the test as we do
on Linux and BSDs.  Extend the fix from commit 4b537c59 (Tests:
Handle that root users on linux can always write to files, 2020-03-30)
and commit e65c5693 (testSystemTools: apply root-check to more systems,
2021-05-31) to AIX hosts too.