Remove no longer used methods

`find_object_in_recycled_slot` and `memory_location` have not been
used since commit:b99833baec2e567e38758f4fd017c90c7ce57d75.

test/ruby/test_gc_compact.rb

@@ -1,6 +1,5 @@
 # frozen_string_literal: true
 require 'test/unit'
-require 'fiddle'
 require 'etc'
 
 if RUBY_PLATFORM =~ /s390x/
@@ -130,10 +129,6 @@ class TestGCCompact < Test::Unit::TestCase
     refute_predicate compact_stats[:moved], :empty?
   end
 
-  def memory_location(obj)
-    (Fiddle.dlwrap(obj) >> 1)
-  end
-
   def big_list(level = 10)
     if level > 0
       big_list(level - 1)
@@ -146,21 +141,6 @@ class TestGCCompact < Test::Unit::TestCase
     end
   end
 
-  # Find an object that's allocated in a slot that had a previous
-  # tenant, and that tenant moved and is still alive
-  def find_object_in_recycled_slot(addresses)
-    new_object = nil
-
-    100_000.times do
-      new_object = Object.new
-      if addresses.index memory_location(new_object)
-        break
-      end
-    end
-
-    new_object
-  end
-
   def test_complex_hash_keys
     list_of_objects = big_list
     hash = list_of_objects.hash