If any Process instances are destroyed after the ProcessManager is
destroyed, then a segfault will occur.
Fix this by making the lifetime of the ProcessManager explicit, and make
the CameraManager construct and deconstruct (automatically, via a member
variable) the ProcessManager.
Update the tests accordingly.
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>