Replace most of the remaining stdio calls by estream calls.

--

We need to use es_fopen on Windows to cope with non-ascii file names.
This is quite a large but fortunately straightforward change.  At a
very few places we keep using stdio (for example due to the use of
popen).

GnuPG-bug-id: 5098
Signed-off-by: Werner Koch <wk@gnupg.org>

kbx/backend-kbx.c

@@ -126,7 +126,7 @@ create_keybox (const char *filename)
                  filename, gpg_strerror (err));
       goto leave;
     }
-  err = _keybox_write_header_blob (NULL, fp, 1);
+  err = _keybox_write_header_blob (fp, 1);
   es_fclose (fp);
   if (err)
     {