tools: Call sendmail directly from the wks tools.

* tools/send-mail.c, tools/send-mail.h: New.
* tools/wks-util.c: New.
* tools/Makefile.am (gpg_wks_server_SOURCES): Add them.
(gpg_wks_client_SOURCES): Ditto.
* tools/gpg-wks.h (opt): Add fields use_sendmail and output.
* tools/gpg-wks-client.c: Add options --send and --output.  Rename
command --send to --create.
(command_send, send_confirmation_response): Output via wks_send_mime.
* tools/gpg-wks-server.c:  Add options --send and --output.
(send_confirmation_request): Output via wks_send_mime.
(check_and_publish): Add hack for name-value bug.
--

With this code, a dedicated user on the server along with a procmail
script, it was possible to run a basic test.

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

tools/send-mail.h

@@ -0,0 +1,27 @@
+/* send-mail.h - Invoke sendmail or other delivery tool.
+ * Copyright (C) 2016 g10 Code GmbH
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef GNUPG_SEND_MAIL_H
+#define GNUPG_SEND_MAIL_H
+
+gpg_error_t send_mail (estream_t fp);
+gpg_error_t send_mail_to_file (estream_t fp, const char *fname);
+
+
+#endif /*GNUPG_SEND_MAIL_H*/