rb_obj_setup: do not copy RUBY_FL_SEEN_OBJ_ID

	[Bug #20250]

	We're seting up a new instance, so it never had an associated
	object_id.

	proc.c: get rid of `CLONESETUP`
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	[Bug #20253]

	All the way down to Ruby 1.9, `Proc`, `Method`, `UnboundMethod`
	and `Binding` always had their own specific clone and dup routine.

	This caused various discrepancies with how other objects behave
	on `dup` and `clone. [Bug #20250], [Bug #20253].

	This commit get rid of `CLONESETUP` and use the the same codepath
	as all other types, so ensure consistency.

	NB: It's still not accepting the `freeze` keyword argument on `clone`.

	Co-Authored-By: Étienne Barrié <etienne.barrie@gmail.com>

[Feature #19755]

Before (in /tmp/test.rb):

```ruby
Object.class_eval("p __FILE__") # => "(eval)"
```

After:

```ruby
Object.class_eval("p __FILE__") # => "(eval at /tmp/test.rb:1)"
```

This makes it much easier to track down generated code in case
the author forgot to provide a filename argument.

This removes the warning that was added in
3802fb92ff8c83eed3e867db20f72c53932f542d, and switches the behavior
so that the eval does not use the binding's __FILE__ and __LINE__
implicitly.

Fixes [Bug #4352]