libcamera: Convert to pragma once

Remove the verbose #ifndef/#define/#endif pattern for maintaining
header idempotency, and replace it with a simple #pragma once.

This simplifies the headers, and prevents redundant changes when
header files get moved.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>

include/libcamera/transform.h

@@ -5,8 +5,7 @@
  * transform.h - 2D plane transforms
  */
 
-#ifndef __LIBCAMERA_TRANSFORM_H__
-#define __LIBCAMERA_TRANSFORM_H__
+#pragma once
 
 #include <string>
 
@@ -74,5 +73,3 @@ Transform transformFromRotation(int angle, bool *success = nullptr);
 const char *transformToString(Transform t);
 
 } /* namespace libcamera */
-
-#endif /* __LIBCAMERA_TRANSFORM_H__ */