sync check_rvalue_consistency_force()

	check_rvalue_consistency_force() uses is_pointer_to_heap() and
	it should be synchronized with other ractors.
	[Bug #17636]
	---
	 gc.c | 149 ++++++++++++++++++++++++++++++++++---------------------------------
	 1 file changed, 76 insertions(+), 73 deletions(-)