Remove MRB_API from mrb_env_unshare()

include/mruby/proc.h

@@ -30,7 +30,7 @@ struct REnv {
 #define MRB_ENV_UNSHARE_STACK(e) ((e)->cioff = -1)
 #define MRB_ENV_STACK_SHARED_P(e) ((e)->cioff >= 0)
 
-MRB_API void mrb_env_unshare(mrb_state*, struct REnv*);
+void mrb_env_unshare(mrb_state*, struct REnv*);
 
 struct RProc {
   MRB_OBJECT_HEADER;

src/vm.c

@@ -273,7 +273,7 @@ cipush(mrb_state *mrb)
   return ci;
 }
 
-MRB_API void
+void
 mrb_env_unshare(mrb_state *mrb, struct REnv *e)
 {
   if (e == NULL) return;