packaging: force gnutls from contrib on Debian based

We need to force gnutls to be build from our contrib system
on Debian based distrubutions as they build gnutls without
Heartbeat support and we strongly need it.

Change-Id: I247de5d03d5346d5a3ab909caa7298c6e8dfbe14

packaging/rules/debian/rules

@@ -44,7 +44,8 @@ override_dh_auto_configure:
 				--disable-sndfile \
 				--disable-gsm \
 				--disable-speexdsp \
-				--disable-natpmp && \
+				--disable-natpmp \
+				--enable-gnutls && \
 		make list && \
 		make -j$(NO_CPUS) V=1
 	cd daemon && \