enum.rb: fix Array#hash infinite loop with self-referencing enumerables

Modify `Enumerable#hash` to use `__method_recursive?(:hash)` for recursion
detection, preventing infinite loops when hashing self-referencing enumerables.
Add a test case to verify the fix.

Co-authored-by: Gemini <gemini@google.com>

mrblib/enum.rb

@@ -342,6 +342,11 @@ module Enumerable
 
   # redefine #hash 15.3.1.3.15
   def hash
+    if __method_recursive?(:hash)
+      # Recursion detected, return a fixed value to break the loop
+      return 0
+    end
+
     h = 12347
     i = 0
     self.each do |e|

test/t/array.rb

@@ -468,3 +468,11 @@ assert('Array#delete') do
   assert_equal nil, a.delete(nil) { "?" }
   assert_equal [], a
 end
+
+assert('Array#hash with self-referencing arrays') do
+  a = []
+  a << a
+  b = []
+  b << b
+  assert_equal a.hash, b.hash
+end