The inotify watch events are handled "at idle" which could in theory mean
a command could run before any preceeding inotify events have been processed.
This leads to a theoretical race window where those events may have a
signficicant effect on the command.
Add a mechanism to allow us to ensure all pending events are processed before
running commands.
(Bitbake rev: bf76cd7e5881adf264b8ba64e27a5b6ca9df4fde)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>