gst1-libav: bump version

And add tarball hash from release announcement.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/gstreamer1/gst1-libav/gst1-libav.hash

@@ -0,0 +1,2 @@
+# From http://lists.freedesktop.org/archives/gstreamer-announce/2014-September/000329.html
+sha256	833229d2b1aad6549ad0297435516508cc3ac47b166d6393ecdffc34c31a01d3	gst-libav-1.4.3.tar.xz

package/gstreamer1/gst1-libav/gst1-libav.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-GST1_LIBAV_VERSION = 1.4.1
+GST1_LIBAV_VERSION = 1.4.3
 GST1_LIBAV_SOURCE = gst-libav-$(GST1_LIBAV_VERSION).tar.xz
 GST1_LIBAV_SITE = http://gstreamer.freedesktop.org/src/gst-libav