pseudo: Fix race problems

There is a potential issue with the fastop code in pseudo since a process may
exit and allow some other function to run before the server has processed
the commands run by the process. Issues have been see with unpredictable
file permissions.

To avoid this, we ping the server before exitting which guarantees it has
processed the current command queue.

The patch was written by peter.seebach@windriver.com

[YOCTO #5132]

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>