refactor: refactor old IOHelper.

- move pointer left padding macro into single header file.
- move utf8 fopen into single header but not finished.
- add testbench for pointer left padding macro.
- add system pointer size detector according to new migrated features requested.

src/yycc/windows/import_guard_head.hpp

@@ -5,5 +5,5 @@
 // YYC MARK:
 // Since YYCC 2.0 version, we use CMake to handle Windows shitty macros,
 // so we do not need declare WIN32_LEAN_AND_MEAN or NOMINMAX in there.
-// But for keep the pair of this guard, we still keep this header file,
+// But for keeping the pair of this guard, we still keep this header file,
 // although it do nothing.

src/yycc/windows/import_guard_tail.hpp

@@ -6,11 +6,11 @@
 
 #if defined(YYCC_OS_WINDOWS)
 
-// Windows also will generate following macros
-// which may cause the function sign is different in Windows and other platforms.
+// Windows also will generate following macros which may cause 
+// the function sign is different in Windows and other platforms.
 // So we simply remove them.
-// Because #undef will not throw error if there are no matched macro,
-// so we simply #undef them directly.
+// At the same time, because `#undef` will not throw error if there are no matched macro,
+// we can simply use `#undef` to remove them directly.
 #undef GetObject
 #undef GetClassName
 #undef LoadImage