ci: drop `-Wno-error=maybe-uninitialized` from win64 cxx flags #36411

I cannot see any maybe-uninitialized warnings in CI logs, and this passes locally on aarch64.

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External sites

• Code coverage & benchmarks: https://corecheck.dev/bitcoin/bitcoin/pulls/36411
• Ralph review: https://git.fish.foo/bitcoin/bitcoin/pulls/36411#author-ralph

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I cannot see any maybe-uninitialized warnings in CI logs, and this passes locally on aarch64.

This is interesting.

The CI job uses GCC 14.3:

C++ compiler .......................... GNU 14.3.0, /nix/store/wj1z9dwd3w62nfhvvla4bk1f3fq6mxi0-x86_64-w64-mingw32-gcc-wrapper-14.3.0/bin/x86_64-w64-mingw32-g++

However, newer compilers still produce the maybe-uninitialized warning, as noted in #35606 (comment). For example:

• on Fedora:

C++ compiler .......................... GNU 16.2.1, /bin/x86_64-w64-mingw32ucrt-g++

• on macOS + Homebrew:

C++ compiler .......................... GNU 16.2.0, /opt/homebrew/bin/x86_64-w64-mingw32-g++

ACK 963f557a721b279a643db2982893c8aa667416c6 for our current CI job.

lgtm ACK 963f557a721b279a643db2982893c8aa667416c6

thx