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>

Previously, these were not implemented, and Object#== and #eql?
were used.  This tries to check the proc internals to make sure
that procs created from separate blocks are treated as not equal,
but procs created from the same block are treated as equal, even
when the lazy proc allocation optimization is used.

Implements [Feature #14267]