merge revision(s) b3d62a77d928eff01268ca7fa1c1c0966702926d: [Backport #17803]

	[ruby/zlib] Synchronize access to zstream to prevent segfault in
	 multithreaded use

	I'm not sure whether this handles all multithreaded use cases,
	but this handles the example that crashes almost immediately
	and does 10,000,000 total deflates using 100 separate threads.

	To prevent the tests from taking forever, the committed test
	for this uses only 10,000 deflates across 10 separate threads,
	which still causes a segfault in the previous implementation
	almost immediately.

	Fixes [Bug #17803]

	https://github.com/ruby/zlib/commit/4b1023b3f2
	---
	 ext/zlib/zlib.c        | 33 ++++++++++++++++++++++++++-
	 test/zlib/test_zlib.rb | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++
	 2 files changed, 93 insertions(+), 1 deletion(-)

0 files changed, 0 insertions, 0 deletions