Include the header file corresponding to the source file in the very
first position. This complies with the Google C++ coding style
guideliens, and helps ensuring that the headers are self-contained.
Three bugs are already caught by this change (missing includes or
forward declarations) in device_enumerator.h, event_dispatcher_poll.h
and pipeline_handler.h. Fix them.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>