Rename singleton to initialized_singleton

Use #pragma once instead of guard definitions in every header

components/f4ll/inc/f4ll/str_util.h

@@ -5,8 +5,7 @@
  *      Author: compi
  */
 
-#ifndef _STM32PLUS_STRUTIL_H_
-#define _STM32PLUS_STRUTIL_H_
+#pragma once
 
 #include <stddef.h>
 #include <inttypes.h>
@@ -27,5 +26,3 @@ char tochr(const uint8_t in, const uint8_t upper);
 #ifdef __cplusplus
 }
 #endif
-
-#endif /* _STM32PLUS_STRUTIL_H_ */