Revert https://github.com/ruby/ruby/pull/2486

This reverts commits: 10d6a3aca7 8ba48c1b85 fba8627dc1 dd883de5ba
6c6a25feca 167e6b48f1 7cb96d41a5 3207979278 595b3c4fdd 1521f7cf89
c11c5e69ac cf33608203 3632a812c0 f56506be0d 86427a3219 .

The reason for the revert is that we observe ABA problem around
inline method cache.  When a cache misshits, we search for a
method entry.  And if the entry is identical to what was cached
before, we reuse the cache.  But the commits we are reverting here
introduced situations where a method entry is freed, then the
identical memory region is used for another method entry.  An
inline method cache cannot detect that ABA.

Here is a code that reproduce such situation:

```ruby
require 'prime'

class << Integer
  alias org_sqrt sqrt
  def sqrt(n)
    raise
  end

  GC.stress = true
  Prime.each(7*37){} rescue nil # <- Here we populate CC
  class << Object.new; end

  # These adjacent remove-then-alias maneuver
  # frees a method entry, then immediately
  # reuses it for another.
  remove_method :sqrt
  alias sqrt org_sqrt
end

Prime.each(7*37).to_a # <- SEGV
```

1 files changed, 1 insertions, 1 deletions

diff --git a/id_table.h b/id_table.h
index 19181190ea..abd9eb5f38 100644
--- a/id_table.h
+++ b/id_table.h
@@ -10,6 +10,7 @@ enum rb_id_table_iterator_result {
     ID_TABLE_STOP     = ST_STOP,
     ID_TABLE_DELETE   = ST_DELETE,
     ID_TABLE_REPLACE  = ST_REPLACE,
+    ID_TABLE_ITERATOR_RESULT_END
 };
 
 struct rb_id_table *rb_id_table_create(size_t size);
@@ -28,7 +29,6 @@ typedef enum rb_id_table_iterator_result rb_id_table_foreach_func_t(ID id, VALUE
 typedef enum rb_id_table_iterator_result rb_id_table_foreach_values_func_t(VALUE val, void *data);
 void rb_id_table_foreach(struct rb_id_table *tbl, rb_id_table_foreach_func_t *func, void *data);
 void rb_id_table_foreach_with_replace(struct rb_id_table *tbl, rb_id_table_foreach_func_t *func, rb_id_table_update_callback_func_t *replace, void *data);
-void rb_id_table_foreach_with_replace_with_key(struct rb_id_table *tbl, rb_id_table_foreach_func_t *func, rb_id_table_update_callback_func_t *replace, void *data, bool needkey);
 void rb_id_table_foreach_values(struct rb_id_table *tbl, rb_id_table_foreach_values_func_t *func, void *data);
 
 #endif	/* RUBY_ID_TABLE_H */