The commit a32c0f3df4b6bcd1d2e93f19e8f380bb890cd507 introduced code to
silence MSVC's "warning C4996: The POSIX name for this item is
deprecated."

However, it exhibits several issues:
1. The aliases may leak into code outside the `subprocess.hpp` header.
2. They are unnecessarily applied when using the MinGW-w64 toolchain.
3. The fix is incomplete: downstream projects still see C4996 warnings.
4. The implementation lacks documentation.

This change addresses all of the above shortcomings.

Co-authored-by: Luke Dashjr <luke-jr+git@utopios.org>

Github-Pull: arun11299/cpp-subprocess#112
Rebased-From: 778543b2f2ca7f5d1c4f0241b635bbb265d750dd

The commit a32c0f3df4b6bcd1d2e93f19e8f380bb890cd507 introduced code to
silence MSVC's "warning C4996: The POSIX name for this item is
deprecated."

However, it exhibits several issues:
1. The aliases may leak into code outside the `subprocess.hpp` header.
2. They are unnecessarily applied when using the MinGW-w64 toolchain.
3. The fix is incomplete: downstream projects still see C4996 warnings.
4. The implementation lacks documentation.

This change addresses all of the above shortcomings.

Github-Pull: arun11299/cpp-subprocess#112
Rebased-From: 778543b2f2ca7f5d1c4f0241b635bbb265d750dd

Co-authored-by: Luke Dashjr <luke-jr+git@utopios.org>

The commit a32c0f3df4b6bcd1d2e93f19e8f380bb890cd507 introduced code to
silence MSVC's "warning C4996: The POSIX name for this item is
deprecated."

However, it exhibits several issues:
1. The aliases may leak into code outside the `subprocess.hpp` header.
2. They are unnecessarily applied when using the MinGW-w64 toolchain.
3. The fix is incomplete: downstream projects still see C4996 warnings.
4. The implementation lacks documentation.

This change addresses all of the above shortcomings.

Github-Pull: arun11299/cpp-subprocess#112
Rebased-From: 778543b2f2ca7f5d1c4f0241b635bbb265d750dd

Co-authored-by: Luke Dashjr <luke-jr+git@utopios.org>

cd95c9d subprocess: check and handle fcntl(F_GETFD) failure (Tomás Andróil)
b7288de subprocess: Proper implementation of wait() on Windows (Haowen Liu)
7423214 subprocess: Do not escape double quotes for command line arguments on Windows (Hennadii Stepanov)
bb9ffea subprocess: Explicitly define move constructor of Streams class (Shunsuke Shimizu)
174bd43 subprocess: Avoid leaking POSIX name aliases beyond `subprocess.h` (Hennadii Stepanov)
7997b76 subprocess: Fix cross-compiling with mingw toolchain (Hennadii Stepanov)
6476304 subprocess: Get Windows return code in wait() (Haowen Liu)
d3f511b subprocess: Fix string_arg when used with rref (Haowen Liu)
2fd3f2f subprocess: Fix memory leaks (Haoran Peng)

Pull request description:

  Most of these changes were developed during work on #29868 and #32342 and have since been upstreamed.

  As they are now merged, this PR backports them to our `src/util/subprocess.h` header.

  Required for #29868.

  A list of the backported PRs:
   - arun11299/cpp-subprocess#106
  - arun11299/cpp-subprocess#110
  - arun11299/cpp-subprocess#109
  - arun11299/cpp-subprocess#99
  - arun11299/cpp-subprocess#112
  - arun11299/cpp-subprocess#107
  - arun11299/cpp-subprocess#113
  - arun11299/cpp-subprocess#116
  - arun11299/cpp-subprocess#117

  The following PRs were skipped for backporting:
  - arun11299/cpp-subprocess#108 because we are not planning to support this feature.
  - arun11299/cpp-subprocess#101 because that change has been already landed in #29849.

ACKs for top commit:
  theStack:
    Light ACK cd95c9d
  laanwj:
    Code review re-ACK cd95c9d

Tree-SHA512: f9b60b932957d2e1cad1d87f2ad8bb68c97136e9735eb78547018a42cc50c4652750367f29462eadb0512c27db1dd8a7d4b17a2f0aeab62b3dbf86db5f51a61c

The commit a32c0f3df4b6bcd1d2e93f19e8f380bb890cd507 introduced code to
silence MSVC's "warning C4996: The POSIX name for this item is
deprecated."

However, it exhibits several issues:
1. The aliases may leak into code outside the `subprocess.hpp` header.
2. They are unnecessarily applied when using the MinGW-w64 toolchain.
3. The fix is incomplete: downstream projects still see C4996 warnings.
4. The implementation lacks documentation.

This change addresses all of the above shortcomings.

Github-Pull: arun11299/cpp-subprocess#112
Rebased-From: 778543b2f2ca7f5d1c4f0241b635bbb265d750dd

Co-authored-by: Luke Dashjr <luke-jr+git@utopios.org>

The commit a32c0f3df4b6bcd1d2e93f19e8f380bb890cd507 introduced code to
silence MSVC's "warning C4996: The POSIX name for this item is
deprecated."

However, it exhibits several issues:
1. The aliases may leak into code outside the `subprocess.hpp` header.
2. They are unnecessarily applied when using the MinGW-w64 toolchain.
3. The fix is incomplete: downstream projects still see C4996 warnings.
4. The implementation lacks documentation.

This change addresses all of the above shortcomings.

Github-Pull: arun11299/cpp-subprocess#112
Rebased-From: 778543b2f2ca7f5d1c4f0241b635bbb265d750dd

Co-authored-by: Luke Dashjr <luke-jr+git@utopios.org>

The commit a32c0f3df4b6bcd1d2e93f19e8f380bb890cd507 introduced code to
silence MSVC's "warning C4996: The POSIX name for this item is
deprecated."

However, it exhibits several issues:
1. The aliases may leak into code outside the `subprocess.hpp` header.
2. They are unnecessarily applied when using the MinGW-w64 toolchain.
3. The fix is incomplete: downstream projects still see C4996 warnings.
4. The implementation lacks documentation.

This change addresses all of the above shortcomings.

Github-Pull: arun11299/cpp-subprocess#112
Rebased-From: 778543b2f2ca7f5d1c4f0241b635bbb265d750dd

Co-authored-by: Luke Dashjr <luke-jr+git@utopios.org>

The commit a32c0f3df4b6bcd1d2e93f19e8f380bb890cd507 introduced code to
silence MSVC's "warning C4996: The POSIX name for this item is
deprecated."

However, it exhibits several issues:
1. The aliases may leak into code outside the `subprocess.hpp` header.
2. They are unnecessarily applied when using the MinGW-w64 toolchain.
3. The fix is incomplete: downstream projects still see C4996 warnings.
4. The implementation lacks documentation.

This change addresses all of the above shortcomings.

Github-Pull: arun11299/cpp-subprocess#112
Rebased-From: 778543b2f2ca7f5d1c4f0241b635bbb265d750dd

Co-authored-by: Luke Dashjr <luke-jr+git@utopios.org>

Github-Pull: bitcoin#32358
Rebased-From: 174bd43