Jonathan Marler authored Mar 27, 2021 and Daniel Stone committed Apr 10, 2021

fixes issue #484 (race condition with message to/from weston launch)

The race condition occurs after weston sends the WESTON_LAUNCHER_OPEN
message to weston-launch.  The race is between when weston-launch replies
with the fd handle versus weston-launch sending an activation message.  If
weston-launch sends an activation message before sending the fd handle,
then weston will be in an invalid state.

To fix this, I modified the fd handle reply that weston-launch sends to
include a message id at the beginning, which I called
WESTON_LAUNCHER_OPEN_REPLY.  Along with this, weston now inspects the
first part of any reply to determine whether it is an activation message
or a reply to the OPEN message.  In the newly handled case that it's an
activation message, it tracks whether the latest result is a deactivate
message and stores it in a flag to be handled once the open function has
completed.

Signed-off-by: Jonathan Marler <johnnymarler@gmail.com>