Work around a broken test for libavformat version.

N.B. This change is in the upstream CVS HEAD, but is not in the latest
released tarball. When the next release tarball is made available, this
patch can be removed.

Signed-off-by: Simon Dawson <spdawson@gmail.com>

diff -Nurp a/metadata.c b/metadata.c
--- a/metadata.c	2012-06-29 22:11:29.000000000 +0100
+++ b/metadata.c	2013-05-04 22:22:47.128202396 +0100
@@ -110,7 +110,7 @@ lav_open(AVFormatContext **ctx, const ch
 static inline void
 lav_close(AVFormatContext *ctx)
 {
-#if LIBAVFORMAT_VERSION_INT >= ((53<<16)+(2<<8)+0)
+#if LIBAVFORMAT_VERSION_INT >= ((53<<16)+(17<<8)+0)
 	avformat_close_input(&ctx);
 #else
 	av_close_input_file(ctx);