git-compat-util: include declaration for unix sockets in windows

Available since Windows 10 release 1803 and Windows Server 2019.

NO_UNIX_SOCKETS is still the default for Windows builds, as they need
to keep backward compatibility with releases up to Windows 7, but allow
including the header otherwise.

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-compat-util.h

@@ -160,6 +160,9 @@
 # endif
 #define WIN32_LEAN_AND_MEAN  /* stops windows.h including winsock.h */
 #include <winsock2.h>
+#ifndef NO_UNIX_SOCKETS
+#include <afunix.h>
+#endif
 #include <windows.h>
 #define GIT_WINDOWS_NATIVE
 #endif