before that, accel data was all 0, but since the gyrosim also publishes
accel data, it was not a problem.

The thread name is used from within the entry of the new thread, but the
provided name could live on the stack of the caller thread. Thus we need to
copy the name.

Just to make sure the user sees the message.

The simulated timer interrupt always adds a new scheduled work task, which
is called from the work queue thread. Sending the signal creates measurable
overhead (~5% of the px4 CPU runtime) and is unnecessary, since the thread
is not sleeping anyway.

this makes it consistent with other functions, like px4_task_spawn_cmd()
and px4_task_kill()

With this change only builds for NuttX which are very much flash size
constraint are optimized for size. All other builds (e.g. SITL,
Snapdragon, etc.) are left at the default for debugging or -O2 for the
usual use.

It makes more sense to set the optimization flags on a platform basis
instead of individually for each module. This allows for different
optimization options for SITL, NuttX, Snapdragon, etc.

This fixes a corner case where the first advertise/publish of a
vehicle_command_ack was missed. What happened was that the
orb_subscribe_multi was not called until the topic had been published
and therefore orb_exists was happy. This means that by the time
orb_subscribe_multi was finally called, the first vehicle_command_ack
was already history and not detected by orb_check.

This changed adds a flag to the MavlinkOrbSubscription which tells it to
subscribe to a topic from the beginning.

- deploy all branches to s3

now the files are equal

DF Update: Use common CMake version so Darwin handling is correct in PX4

Update DF to use proper constants

Update DF

Output CMake version