pseudo: Add in ability to flush database with shutdown request

Pulls in:
  pseudo_db: Flush DB if there is a shutdown request
  fcntl: Add support for fcntl F_GETPIPE_SZ and F_SETPIPE_SZ (test fix)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 0882095d)
Signed-off-by: Steve Sakoman <steve@sakoman.com>