Method#== returns false for aliased methods that should be equal

Method#== returns false for aliased methods that should be equal to the original method.

## Reproduction Steps

Create test.rb:
```ruby
class Test
  def a; end
  alias b a
end
t = Test.new
p(t.method(:b) == t.method(:a))
```

Current behavior (mruby):
```sh
$ ./bin/mruby test.rb
false
```

Expected behavior (CRuby):
```sh
$ ruby test.rb
true
```
