Clear all refined CCs on reopening refinement mod

In cfd7729ce7 we started using inline
caches for refinements. However, we weren't clearing inline caches when
defined on a reopened refinement module.

Fixes [Bug #20246]

test/ruby/test_refinement.rb

@@ -1606,18 +1606,35 @@ class TestRefinement < Test::Unit::TestCase
       end
 
       using R
+      def m
+        C.new.m
+      end
+
       assert_equal(:foo, C.new.m)
+      assert_equal(:foo, m)
 
       module R
         refine C do
+
+          assert_equal(:foo, C.new.m)
+          assert_equal(:foo, m)
+
           alias m m
+
+          assert_equal(:foo, C.new.m)
+          assert_equal(:foo, m)
+
           def m
             :bar
           end
+
+          assert_equal(:bar, C.new.m, "[ruby-core:71423] [Bug #11672]")
+          assert_equal(:bar, m, "[Bug #20285]")
         end
       end
 
       assert_equal(:bar, C.new.m, "[ruby-core:71423] [Bug #11672]")
+      assert_equal(:bar, m, "[Bug #20285]")
     end;
   end
 

vm_method.c

@@ -301,6 +301,7 @@ rb_clear_method_cache(VALUE klass_or_module, ID mid)
             VALUE refined_class = rb_refinement_module_get_refined_class(module);
             rb_clear_method_cache(refined_class, mid);
             rb_class_foreach_subclass(refined_class, clear_iclass_method_cache_by_id_for_refinements, mid);
+            rb_clear_all_refinement_method_cache();
         }
         rb_class_foreach_subclass(module, clear_iclass_method_cache_by_id, mid);
     }