Replace guards with pragma once

load_library.h

@@ -1,6 +1,4 @@
-#ifndef LIB_LOAD_HEADER
-#define LIB_LOAD_HEADER
-
+#pragma once
 typedef void *LIB_Library;
 
 LIB_Library LIB_LoadLibrary(char *str);
@@ -10,5 +8,3 @@ bool LIB_UnloadLibrary(LIB_Library lib);
 #ifndef LIB_EXPORT
     #define LIB_EXPORT __declspec(dllexport)
 #endif
-
-#endif