w32: Make pipes really pollable.

* common/exectool.c (gnupg_exec_tool_stream) [W32]: Use _get_osfhandle
to print the fd for the command line.
* common/exechelp-w32.c (create_pipe_and_estream): Use es_sysopen so
that the streams are actually pollable.
--

This addresses two bugs:

 - Using the "-&@INEXTRA@" kludges requires that we pass the value of
   the handle on the command line and not the libc fd.

 - gpgrt_poll requires the use of the ReadFile/WriteFile backend which
   is currently only used when the stream has been created with
   gpgrt_sysopen.

Signed-off-by: Werner Koch <wk@gnupg.org>

common/exectool.c

@@ -384,7 +384,12 @@ gnupg_exec_tool_stream (const char *pgmname, const char *argv[],
       /* Now find the argument marker and replace by the pipe's fd.
          Yeah, that is an ugly non-thread safe hack but it safes us to
          create a copy of the array.  */
+#ifdef HAVE_W32_SYSTEM
+      snprintf (extrafdbuf, sizeof extrafdbuf, "-&%lu",
+                (unsigned long)(void*)_get_osfhandle (extrapipe[0]));
+#else
       snprintf (extrafdbuf, sizeof extrafdbuf, "-&%d", extrapipe[0]);
+#endif
       for (argsaveidx=0; argv[argsaveidx]; argsaveidx++)
         if (!strcmp (argv[argsaveidx], "-&@INEXTRA@"))
           {