Sort the filenames to get a consistent result between machines of the same
architecture.
Also, sort FTS_D entries after other entries so kldxref -R works properly in
the uncommon case that a directory contains both subdirectories and modules.
Previously, this may have happened to work, depending on the order of files
in the directory.
PR: bin/182098
Submitted by: Derek Schrock (original version)
Tested by: Derek Schrock
Approved by: re (delphij)
MFC after: 1 week
64b622034f