The revokex test does not work when the scratch directory is created on NFS.
Given the nature of NFS, it likely can never work without looking like a
security hole since O_SEARCH would rely on the server knowing that the
directory did have +x at the time of open and that it's OK for it to have
been revoked based on POSIX specification for O_SEARCH.
This does mean that O_SEARCH is only partially functional on NFS in general,
but I suspect the execute bit getting revoked in the process is likely not
common.
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D23573
14d3b06919