encoding.c: remove rb_gc_mark_encodings

rb_gc_mark_encodings has been empty for a decade
(since r17875 / 28b216ac45).
Just remove it and its only caller in gc.c

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63582 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

encoding.c

@@ -260,11 +260,6 @@ rb_find_encoding(VALUE enc)
     return rb_enc_from_index(idx);
 }
 
-void
-rb_gc_mark_encodings(void)
-{
-}
-
 static int
 enc_table_expand(int newsize)
 {

gc.c

@@ -4850,9 +4850,6 @@ gc_mark_roots(rb_objspace_t *objspace, const char **categoryp)
     MARK_CHECKPOINT("machine_context");
     mark_current_machine_context(objspace, ec);
 
-    MARK_CHECKPOINT("encodings");
-    rb_gc_mark_encodings();
-
     /* mark protected global variables */
     MARK_CHECKPOINT("global_list");
     for (list = global_list; list; list = list->next) {

internal.h

@@ -1189,7 +1189,6 @@ void Init_ext(void);
 
 /* encoding.c */
 ID rb_id_encoding(void);
-void rb_gc_mark_encodings(void);
 #ifdef RUBY_ENCODING_H
 rb_encoding *rb_enc_get_from_index(int index);
 rb_encoding *rb_enc_check_str(VALUE str1, VALUE str2);