Some devices like Android smartphones have displays which are
rotated, meaning the compositor needs to rotate its output.
Add support for this to the compute compositor by rotating the
contents of the textures it uses for distortion lookups. This
requires postponing the calculation of that texture and adding
code to recreate it if the rotation changes (which is allowed,
but unlikely to happen in practice.)
Make sure to stop the USB thread before destroying the debug sink
as cancelling the transfers is not sufficient to guarantee
there will be no final callback (or one in progress)
This solves a problem where OpenXR timestamps could become invalid
(negative) in certain circumstances:
The timestamps that the OpenXR state tracker returned were offset such
that they appeared to start at OpenXR application startup time.
However monado-service is a long running service using system timestamps.
Because of this, if monado-service started work using a system timestamp
acquired before an OpenXR application started, then this system timestamp
could not be converted into an OpenXR without becoming invalid.
With this change, the OpenXR timestamps for OpenXR applications are offset
such that they appear to start at monado-service startup time instead.
As a side effect, all OpenXR applications connected to the same
monado-service instance will receive timestamps from the same domain.
Use a sink in the middle of the stream to correct for v4l2 timestamps with
hardware timestamps to monotonic clock.
This sink, together with other utilities related to data streaming, lives in a
new vive_source entity, with similar functionality to wmr_source or rs_source.
The vive_source lifetime is managed by the builder xfctx, which prevents
deallocation dependencies between vive_device and the v4l2_fs to cause segfaults.