[struct_pack] update rule for enabling [[likely]] (#696)

MSVC intentionally defined __cplusplus to 199711L, ignoring the actual standard, hence MACRO definitions of `SP_LIKELY` and `SP_UNLIKELY` go to wrong branches in MSVC build.

Author: scuzqy

include/ylt/struct_pack/marco.h

@@ -31,19 +31,14 @@
 #define STRUCT_PACK_MAY_INLINE inline
 #endif
 
-#if __has_cpp_attribute(likely) && __cplusplus >= 202002L
+#if __has_cpp_attribute(likely) && __has_cpp_attribute(unlikely)
 #define SP_LIKELY(expr) (expr) [[likely]]
-#elif __GNUC__
-#define SP_LIKELY(expr) (__builtin_expect(!!(expr), 1))
-#else
-#define SP_LIKELY(expr) (expr)
-#endif
-
-#if __has_cpp_attribute(unlikely) && __cplusplus >= 202002L
 #define SP_UNLIKELY(expr) (expr) [[unlikely]]
 #elif __GNUC__
+#define SP_LIKELY(expr) (__builtin_expect(!!(expr), 1))
 #define SP_UNLIKELY(expr) (__builtin_expect(!!(expr), 0))
 #else
+#define SP_LIKELY(expr) (expr)
 #define SP_UNLIKELY(expr) (expr)
 #endif