Reorganize defines related to `MRB_INLINE`; ref #4391

include/mruby/common.h

@@ -54,12 +54,12 @@ MRB_BEGIN_DECL
 #endif
 
 /** Declare a function as always inlined. */
-#if defined(_MSC_VER)
-# define MRB_INLINE static __inline
-#else
-# define MRB_INLINE static inline
+#if defined _MSC_VER && _MSC_VER < 1900
+# ifndef __cplusplus
+#  define inline __inline
+# endif
 #endif
-
+#define MRB_INLINE static inline
 
 /** Declare a public MRuby API function. */
 #if defined(MRB_BUILD_AS_DLL)

include/mruby/value.h

@@ -73,9 +73,6 @@ MRB_API double mrb_float_read(const char*, char**);
 #endif
 
 #if defined _MSC_VER && _MSC_VER < 1900
-# ifndef __cplusplus
-#  define inline __inline
-# endif
 # include <stdarg.h>
 MRB_API int mrb_msvc_vsnprintf(char *s, size_t n, const char *format, va_list arg);
 MRB_API int mrb_msvc_snprintf(char *s, size_t n, const char *format, ...);