Mknod is now implemented by mount, mount2 and cmount, so exercise it from
the shared vfstest suite: create a regular file (S_IFREG) through the
mounted path and check it reads back as a 0-byte regular file. This is the
path the kernel NFS server drives when a client creates a file over an
exported mount.
Before this there was no shared coverage for Mknod; it now runs against
each backend via RunTests.
Suggested in #9548.
Signed-off-by: Sandy Luppino <s.luppino@opendrives.com>
c1b5756eec