Support for the unix socket has existed both in BSD and Linux for the
longest time, but not on Windows. Since Windows 10 build 17063 [1],
the native support for the unix socket has came to Windows. Starting
this build, two Win32 processes can use the AF_UNIX address family
over Winsock API to communicate with each other.

Introduce a new build time config option CONFIG_AF_UNIX when the build
host has such a capability, and a run-time check afunix_available() for
Windows host in the QEMU sockets util codes.

[1] https://devblogs.microsoft.com/commandline/af_unix-comes-to-windows/

Changes in v2:
- move #include <afunix.h> to os-win32.h
- define WIN_BUILD_AF_UNIX only when CONFIG_WIN32
- drop #include <afunix.h> as it is now already included in osdep.h
- new patch: tests/unit: Update test-io-channel-socket.c for Windows

Bin Meng (6):
  util/qemu-sockets: Replace the call to close a socket with
    closesocket()
  util/oslib-win32: Add a helper to get the Windows version
  qga/commands-win32: Use os_get_win_version()
  util/qemu-sockets: Enable unix socket support on Windows
  chardev/char-socket: Update AF_UNIX for Windows
  tests/unit: Update test-io-channel-socket.c for Windows

 meson.build                         |  6 ++++
 include/sysemu/os-win32.h           |  6 ++++
 chardev/char-socket.c               |  4 ++-
 qga/commands-win32.c                | 27 +---------------
 tests/unit/test-io-channel-socket.c | 16 ++++++++--
 util/oslib-win32.c                  | 15 +++++++++
 util/qemu-sockets.c                 | 49 +++++++++++++++++++++++------
 7 files changed, 85 insertions(+), 38 deletions(-)

-- 
2.34.1