Merge bitcoin/bitcoin#22824: refactor: remove RecursiveMutex cs_nBlockSequenceId

0bd882b7405414b5355e69a9fdcd7a533e504b6b refactor: remove RecursiveMutex cs_nBlockSequenceId (Sebastian Falbesoner)

Pull request description:

  The RecursiveMutex `cs_nBlockSequenceId` is only used at one place in `CChainState::ReceivedBlockTransactions()` to atomically read-and-increment the nBlockSequenceId member:

  https://github.com/bitcoin/bitcoin/blob/83daf47898f8a79cb20d20316c64becd564cf54c/src/validation.cpp#L2973-L2976

  ~~For this simple use-case, we can make the member `std::atomic` instead to achieve the same result (see https://en.cppreference.com/w/cpp/atomic/atomic/operator_arith).~~

  ~~This is related to #19303. As suggested in the issue, I first planned to change the `RecursiveMutex` to `Mutex` (still possible if the change doesn't get Concept ACKs), but using a Mutex for this simple operation seems to be overkill. Note that at the time when this mutex was introduced (PR #3370, commit 75f51f2a63e0ebe34ab290c2b7141dd240b98c3b) `std::atomic` were not used in the codebase yet -- according to `git log -S std::atomic` they have first appeared in 2016 (commit 7e908c7b826cedbf29560ce7a668af809ee71524), probably also because the compilers didn't support them properly earlier.~~

  At this point, the cs_main lock is set, hence we can use a plain int for the member and mark it as guarded by cs_main.

ACKs for top commit:
  Zero-1729:
    ACK 0bd882b
  promag:
    Code review ACK 0bd882b7405414b5355e69a9fdcd7a533e504b6b.
  hebasto:
    ACK 0bd882b7405414b5355e69a9fdcd7a533e504b6b

Tree-SHA512: 435271ac8f877074099ddb31436665b500e555f7cab899e5c8414af299b154d1249996be500e8fdeff64e4639bcaf7386e12510b738ec6f20e415e7e35afaea9

0 files changed, 0 insertions, 0 deletions