Use lowercase Windows headers for MinGW

[Garcia6l20]

This fixes the Windows SDK include spellings used by the MinGW path.

On native Windows this does not change behavior, but on case-sensitive MinGW installs several mixed-case includes fail to resolve. I hit that while building with /usr/bin/x86_64-w64-mingw32-g++ from Linux.

• Switched the Windows SDK includes in the IOCP headers to the lowercase spellings MinGW ships.
• Switched the same includes in the Windows fault tests.

I used this to verify the fix:

cmake -S . -B build/corosio-mingw-tests \
  -DCMAKE_CXX_COMPILER=/usr/bin/x86_64-w64-mingw32-g++ \
  -DBUILD_TESTING=ON

cmake --build build/corosio-mingw-tests --target tests

One test still crashes under Wine, but that looks Wine-specific:
corosio/test/unit/iocp_paths.cpp calls WSASocketW(AF_UNIX, SOCK_STREAM, 0, nullptr, 0, WSA_FLAG_OVERLAPPED) which fails with WSAEAFNOSUPPORT under Wine.

[cppalliance-bot]

An automated preview of the documentation is available at https://359.corosio.prtest3.cppalliance.org/index.html

If more commits are pushed to the pull request, the docs will rebuild at the same URL.

2026-09-21 05:05:37 UTC

[cppalliance-bot]

GCOVR code coverage report https://359.corosio.prtest3.cppalliance.org/gcovr/index.html
LCOV code coverage report https://359.corosio.prtest3.cppalliance.org/genhtml/index.html
Coverage Diff Report https://359.corosio.prtest3.cppalliance.org/diff-report/index.html

Build time: 2026-09-21 05:15:10 UTC