merge revision(s) bbedd29b6e98ef6e3fc2ce2b358d2b509b7cd1bb: [Backport #18117]

	[Bug #18117] Fix Ractor race condition with GC

	rb_objspace_reachable_objects_from requires that the GC not be active.
	Since the Ractor barrier is not executed for incremental sweeping,
	Ractor may call rb_objspace_reachable_objects_from after sweeping
	has started to share objects. This causes a crash that looks like
	the following:

	```
	<internal:ractor>:627: [BUG] rb_objspace_reachable_objects_from() is not supported while during_gc == true
	```

	Co-authored-by: Vinicius Stock <vinicius.stock@shopify.com>
	---
	 bootstraptest/test_ractor.rb | 15 +++++++++++++++
	 ractor.c                     | 12 ++++++++++--
	 2 files changed, 25 insertions(+), 2 deletions(-)

0 files changed, 0 insertions, 0 deletions