package/gnutls: security bump to 3.6.7.1

package/gnutls: security bump to 3.6.7.1

Fixes the following security issues:

 * CVE-2019-3836: It was discovered in gnutls before version 3.6.7 upstream
   that there is an uninitialized pointer access in gnutls versions 3.6.3 or
   later which can be triggered by certain post-handshake messages

 * CVE-2019-3829: A vulnerability was found in gnutls versions from 3.5.8
   before 3.6.7. A memory corruption (double free) vulnerability in the
   certificate verification API. Any client or server application that
   verifies X.509 certificates with GnuTLS 3.5.8 or later is affected.

3.6.7.1 is identical to 3.6.7, but fixes a packaging issue in the release
tarball:

https://lists.gnutls.org/pipermail/gnutls-devel/2019-April/013086.html

HTTP URLs changed to HTTPS in COPYING, so update license hash.

Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>