merge revision(s) cd4f5b13,8db269ed,ab63f6d8: [Backport #18140]

	Guard array when appending

	This prevents early collection of the array.  The GC doesn't see the
	array on the stack when Ruby is compiled with optimizations enabled

	[ruby-core:105099] [Bug #18140]
	---
	 array.c                 | 1 +
	 test/ruby/test_array.rb | 6 ++++++
	 2 files changed, 7 insertions(+)

	Guard array when appending

	This prevents early collection of the array.  The GC doesn't see the
	array on the stack when Ruby is compiled with optimizations enabled

	Thanks @jhaberman for the test case

	[ruby-core:105099] [Bug #18140]
	---
	 ext/-test-/array/concat/depend          | 321 ++++++++++++++++++++++++++++++++
	 ext/-test-/array/concat/extconf.rb      |   2 +
	 ext/-test-/array/concat/to_ary_conact.c |  64 +++++++
	 test/-ext-/array/test_to_ary_concat.rb  |  20 ++
	 4 files changed, 407 insertions(+)
	 create mode 100644 ext/-test-/array/concat/depend
	 create mode 100644 ext/-test-/array/concat/extconf.rb
	 create mode 100644 ext/-test-/array/concat/to_ary_conact.c
	 create mode 100644 test/-ext-/array/test_to_ary_concat.rb

	Refined test [Bug #18140]

	---
	 ext/-test-/array/concat/to_ary_conact.c | 48 +++++++--------------------------
	 test/ruby/test_array.rb                 |  5 +++-
	 2 files changed, 13 insertions(+), 40 deletions(-)