merge revision(s) d6c5a30c,a2d4e1cd: [Backport #18392]

	ObjectSpace::WeakMap#inspect: check if living object [Bug #18392]

	---
	 gc.c                      | 29 +++++++++++++++++++++++------
	 test/ruby/test_weakmap.rb |  9 +++++++++
	 2 files changed, 32 insertions(+), 6 deletions(-)

	Fixed the check order in wmap_live_p [Bug #18392]

	Check if the object is a pointer to heap before check the flag in
	that object.
	---
	 gc.c | 35 ++++++++++++++++++++++-------------
	 1 file changed, 22 insertions(+), 13 deletions(-)