gnutls: security bump to version 3.2.20

Fixes:
CVE-2014-8564 / GNUTLS-SA-2014-5 - Sean Burford reported that the
encoding of elliptic curves parameters GnuTLS 3 is vulnerable to a
denial of service (heap corruption). It affects clients and servers
which print information about the peer's certificate, e.g., the key ID,
and can be exploited via a specially crafted X.509 certificate.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/gnutls/gnutls.hash

@@ -1,2 +1,2 @@
 # Locally calculated after checking pgp signature
-sha256	a20d95a434a670afe5ce66430ae56151bbbe14456a0517ce775c46b1d4183dcf	gnutls-3.2.19.tar.xz
+sha256	7967057e78c3ed968e524a07ab262681219b73001ab8e75cbc4f1a506abdb598	gnutls-3.2.20.tar.xz

package/gnutls/gnutls.mk

@@ -5,7 +5,7 @@
 ################################################################################
 
 GNUTLS_VERSION_MAJOR = 3.2
-GNUTLS_VERSION = $(GNUTLS_VERSION_MAJOR).19
+GNUTLS_VERSION = $(GNUTLS_VERSION_MAJOR).20
 GNUTLS_SOURCE = gnutls-$(GNUTLS_VERSION).tar.xz
 GNUTLS_SITE = ftp://ftp.gnutls.org/gcrypt/gnutls/v$(GNUTLS_VERSION_MAJOR)
 GNUTLS_LICENSE = GPLv3+ LGPLv2.1+