[unittests][Support] AIX: Skip sticky bit file tests

On AIX, attempting (without root) to set the sticky bit on a file with
the `chmod` utility will give:
chmod: not all requested changes were made to <file>

The same occurs when modifying other permission bits on a file with the
sticky bit already set.

It seems that the `chmod` function will report success despite failing
to set the sticky bit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350735 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed