Update libmultiprocess subtree to fix intermittent mptest hang #33412

1. 
   ryanofsky commented at 10:04 am on September 17, 2025: contributor

   Includes:

   • https://github.com/bitcoin-core/libmultiprocess/pull/207
   • https://github.com/bitcoin-core/libmultiprocess/pull/208
   • https://github.com/bitcoin-core/libmultiprocess/pull/211
   • https://github.com/bitcoin-core/libmultiprocess/pull/201

   The last change fixes the test hang reported #33244

   The changes can be verified by running test/lint/git-subtree-check.sh src/ipc/libmultiprocess as described in developer notes and lint instructions

2. Squashed 'src/ipc/libmultiprocess/' changes from 13424cf2ecc1..47d79db8a552

   47d79db8a552 Merge bitcoin-core/libmultiprocess#201: bug: fix mptest hang, ProxyClient<Thread> deadlock in disconnect handler
   f15ae9c9b9fb Merge bitcoin-core/libmultiprocess#211: Add .gitignore
   4a269b21b8c8 bug: fix ProxyClient<Thread> deadlock if disconnected as IPC call is returning
   85df96482c49 Use try_emplace in SetThread instead of threads.find
   ca9b380ea91a Use std::optional in ConnThreads to allow shortening locks
   9b0799113557 doc: describe ThreadContext struct and synchronization requirements
   d60db601ed9b proxy-io.h: add Waiter::m_mutex thread safety annotations
   4e365b019a9f ci: Use -Wthread-safety not -Wthread-safety-analysis
   15d7bafbb001 Add .gitignore
   fe1cd8c76131 Merge bitcoin-core/libmultiprocess#208: ci: Test minimum cmake version in olddeps job
   b713a0b7bfbc Merge bitcoin-core/libmultiprocess#207: ci: output CMake version in CI script
   0f580397c913 ci: Test minimum cmake version in olddeps job
   d603dcc0eef0 ci: output CMake version in CI script
   
   git-subtree-dir: src/ipc/libmultiprocess
   git-subtree-split: 47d79db8a5528097b408e18f7b0bae11a6702d26

   535fa0ad0d
3. Merge commit '535fa0ad0d2637f845beae92ea9dbbbbbe377c74' into pr/subtree-5 c49a43591f
4. DrahtBot renamed this:
   Update libmultiprocess subtree to fix intermittent mptest hang
   Update libmultiprocess subtree to fix intermittent mptest hang
   on Sep 17, 2025
5. 
   DrahtBot commented at 10:04 am on September 17, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/33412.

   Reviews

   See the guideline for information on the review process.

   Type	Reviewers
   ACK	Sjors, TheCharlatan

   If your review is incorrectly listed, please react with 👎 to this comment and the bot will ignore it on the next update.

   LLM Linter (✨ experimental)

   Possible typos and grammar issues:

   • before thread client is -> before the thread client is [missing article makes the sentence awkward and slightly unclear]
   • Synchronization note: \ref callback_threads note applies here as well. -> Synchronization note: the callback_threads note applies here as well. [\ref looks like a Doxygen reference; as written the phrase is redundant/awkward (“note” twice) and the backslash ref makes the sentence unclear in plain English]

   drahtbot_id_5_m

6. 
   fanquake commented at 1:04 pm on September 18, 2025: member

   cc @Sjors
7. 
   Sjors commented at 5:18 pm on September 18, 2025: member

   ACK c49a43591f88dc199cc04e76f3cfcb7ba136f1a6
8. TheCharlatan approved
9. 
   TheCharlatan commented at 9:22 am on September 19, 2025: contributor

   ACK c49a43591f88dc199cc04e76f3cfcb7ba136f1a6
10. fanquake merged this on Sep 19, 2025
11. fanquake closed this on Sep 19, 2025

    ---

Contributors
ryanofsky DrahtBot fanquake Sjors TheCharlatan