libcamera: base: 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/base/utils.h

@@ -4,8 +4,8 @@
  *
  * utils.h - Miscellaneous utility functions
  */
-#ifndef __LIBCAMERA_BASE_UTILS_H__
-#define __LIBCAMERA_BASE_UTILS_H__
+
+#pragma once
 
 #include <algorithm>
 #include <chrono>
@@ -355,5 +355,3 @@ std::basic_ostream<CharT, Traits> &operator<<(std::basic_ostream<CharT, Traits>
 #endif
 
 } /* namespace libcamera */
-
-#endif /* __LIBCAMERA_BASE_UTILS_H__ */