Remove segregated value struct declaration

include/mruby.h

@@ -119,7 +119,6 @@ struct mrb_jmpbuf;
 
 typedef void (*mrb_atexit_func)(struct mrb_state*);
 
-
 typedef struct mrb_state {
   struct mrb_jmpbuf *jmp;
 

src/gc.c

@@ -97,40 +97,6 @@ struct free_obj {
   struct RBasic *next;
 };
 
-typedef struct {
-  union {
-    struct free_obj free;
-    struct RBasic basic;
-    struct RClass klass;
-    struct RProc proc;
-    struct RException exc;
-  } as;
-} infreq_value;
-
-typedef struct {
-  union {
-    struct free_obj free;
-    struct RBasic basic;
-    struct RObject object;
-#ifdef MRB_WORD_BOXING
-    struct RFloat floatv;
-    struct RCptr cptr;
-#endif
-  } as;
-} small_value;
-
-typedef struct {
-  union {
-    struct free_obj free;
-    struct RBasic basic;
-    struct RString string;
-    struct RArray array;
-    struct RHash hash;
-    struct RRange range;
-    struct RData data;
-  } as;
-} large_value;
-
 typedef struct {
   union {
     struct free_obj free;