move mrb_value def to mruby/value.h

include/mruby/object.h

@@ -1,5 +1,5 @@
 /*
-** object.h - Object, NilClass, TrueClass, FalseClass class
+** mruby/object.h - Object, NilClass, TrueClass, FalseClass class
 **
 ** See Copyright Notice in mruby.h
 */
@@ -7,10 +7,6 @@
 #ifndef MRUBY_OBJECT_H
 #define MRUBY_OBJECT_H
 
-#if defined(__cplusplus)
-extern "C" {
-#endif
-
 #define MRUBY_OBJECT_HEADER \
   enum mrb_vtype tt:8; \
   unsigned int color:3;\
@@ -18,7 +14,6 @@ extern "C" {
   struct RClass *c;\
   struct RBasic *gcnext
 
-
 /* white: 011, black: 100, gray: 000 */
 #define MRB_GC_GRAY 0
 #define MRB_GC_WHITE_A 1
@@ -54,8 +49,4 @@ struct RObject {
 #define ROBJECT_IVPTR(v) (((struct RObject*)((v).value.p))->iv)
 #define ROBJECT_NUMIV(v) (ROBJECT_IVPTR(v) ? ROBJECT_IVPTR(v)->size : 0)
 
-#if defined(__cplusplus)
-}  /* extern "C" { */
-#endif
-
 #endif  /* MRUBY_OBJECT_H */