cygwin 3.6.4-1

[Corinna Vinschen]

The following packages have been uploaded to the Cygwin distribution:

* cygwin-3.6.4-1
* cygwin-devel-3.6.4-1
* cygwin-doc-3.6.4-1

Fixes:
------

- Fix unexpected crash when SIGSEGV occurs too frequently.
  Addresses: https://cygwin.com/pipermail/cygwin/2025-May/258153.html

- Make pthread initializer macros compatible with C++ constinit.
  Addresses: https://cygwin.com/pipermail/cygwin/2025-June/258305.html

- Fix creating native symlinks to `..` (it used to target `../../<dir>`
  instead).

- Fix CI (stress-ng) for arm64 windows failure.
  Addresses: https://cygwin.com/pipermail/cygwin/2025-June/258332.html

- Fix handling of invalid 4 byte UTF-8 sequences.
  Addresses: https://cygwin.com/pipermail/cygwin/2025-June/258358.html

- Fix SSH hang with non-cygwin pipe reader.
  Addresses: https://github.com/git-for-windows/git/issues/5682

- Fix unexpected blocking mode change by pipe_data_available()
  Addresses: https://github.com/git-for-windows/git/issues/5682#issuecomment-2997428207

- Fix potential crashing a process PID by accessing /proc/PID/maps
  in parallel.
  Addresses: https://cygwin.com/pipermail/cygwin/2025-May/258198.html

- Fix ACL operations on directories.
  Addresses: https://cygwin.com/pipermail/cygwin/2025-July/258433.html

- Make TCIFLUSH also flush read-ahead data in the master.
  Addresses: https://cygwin.com/pipermail/cygwin/2025-July/258442.html