[PATCH] Fix refinement modification of method visibility in superclass

	Previously, this didn't work correctly, resulting in a
	SystemStackError. This fixes the issue by finding the related
	superclass method entry, and updating the orig_me in the
	refinement method to point to the superclass method.

	Fixes [Bug #21446]

	[PATCH] [Bug #21673] Fix resolving refined module-defined method

	A method defined in a module has no `defined_class`, use the ICLASS
	for it as the `defined_class`.

	ruby2_keywords warnings: Quote non-UTF8 method names fully

	It used to quote only part of the method name because NUL byte in
	the method terminates the C string:

	```
	(irb)> "abcdef".encode("UTF-16LE").bytes
	=> [97, 0, 98, 0, 99, 0, 100, 0, 101, 0, 102, 0]
	```

	```
	expected: /abcdef/
	actual: warning: Skipping set of ruby2_keywords flag for a (method not defined in Ruby)\n".
	```

	Do not respect ruby2_keywords on method/proc with post arguments

	Previously, ruby2_keywords could be used on a method or proc with
	post arguments, but I don't think the behavior is desired:

	```ruby
	def a(*c, **kw) [c, kw] end
	def b(*a, b) a(*a, b) end
	ruby2_keywords(:b)

	b({foo: 1}, bar: 1)
	```

	This changes ruby2_keywords to emit a warning and not set the
	flag on a method/proc with post arguments.

	While here, fix the ruby2_keywords specs for warnings, since they
	weren't testing what they should be testing.  They all warned
	because the method didn't accept a rest argument, not because it
	accepted a keyword or keyword rest argument.

	[Bug #20868] Fix Method#hash to not change after compaction

	The hash value of a Method must remain constant after a compaction, otherwise
	it may not work as the key in a hash table.

	For example:

	    def a; end

	    # Need this method here because otherwise the iseq may be on the C stack
	    # which would get pinned and not move during compaction
	    def get_hash
	      method(:a).hash
	    end

	    puts get_hash # => 2993401401091578131

	    GC.verify_compaction_references(expand_heap: true, toward: :empty)

	    puts get_hash # => -2162775864511574135

	[Bug #20342] Consider wrapped load in `main` methods

Add memory leak test for eval kwargs

	De-dup identical callinfo objects

	Previously every call to vm_ci_new (when the CI was not packable) would
	result in a different callinfo being returned this meant that every
	kwarg callsite had its own CI.

	When calling, different CIs result in different CCs. These CIs and CCs
	both end up persisted on the T_CLASS inside cc_tbl. So in an eval loop
	this resulted in a memory leak of both types of object. This also likely
	resulted in extra memory used, and extra time searching, in non-eval
	cases.

	For simplicity in this commit I always allocate a CI object inside
	rb_vm_ci_lookup, but ideally we would lazily allocate it only when
	needed. I hope to do that as a follow up in the future.

Clear all refined CCs on reopening refinement mod

	In cfd7729ce7a31c8b6ec5dd0e99c67b2932de4732 we started using inline
	caches for refinements. However, we weren't clearing inline caches when
	defined on a reopened refinement module.

	Fixes [Bug #20246]

	Fix [Bug #20246]: Don't set next_head_exact if a capture is called (#9897)

This also removes aliasing rule violations; the anonymous structs were
distinct types from `rb_method_refined_t`.

Previously, we didn't invalidate the method entry wrapped by
VM_METHOD_TYPE_REFINED method entries which could cause calls to
land in the wrong method like it did in the included test.

Do the invalidation, and adjust rb_method_entry_clone() to accommodate
this new invalidation vector.

Fix: cfd7729ce7a31c8b6ec5dd0e99c67b2932de4732
See-also: e201b81f79828c30500947fe8c8ea3c515e3d112

Found through GC.stress + GC.auto_compact crashes in GH-8932.
Previously, the compaction run within `rb_method_entry_alloc()` could
move the `def->body.iseq.cref` and `iseqptr` set up before the call and
leave the `def` pointing to moved addresses. Nothing was marking `def`
during that GC run.

Low probability reproducer:

    GC.stress = true
    GC.auto_compact = true
    arr = []
    alloc = 1000.times.map { [] }
    alloc = nil
    a = arr.first
    GC.start