libcamera: Include header related to source file first

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>

src/libcamera/device_enumerator.cpp

@@ -5,6 +5,8 @@
  * device_enumerator.cpp - Enumeration and matching
  */
 
+#include "device_enumerator.h"
+
 #include <fcntl.h>
 #include <libudev.h>
 #include <string.h>
@@ -13,7 +15,6 @@
 
 #include <libcamera/event_notifier.h>
 
-#include "device_enumerator.h"
 #include "log.h"
 #include "media_device.h"
 #include "utils.h"