demux: bump --cache-secs default value

Change to it 1000 hours, which is "infinite" enough. (Hesitant to use
INFINITY, as that is not in the option's range. The option parser
rejects it because it causes only problems in API users and so on.)

demux/demux.c

@@ -148,7 +148,7 @@ const struct m_sub_options demux_conf = {
         .max_bytes_bw = 50 * 1024 * 1024,
         .donate_fw = 1,
         .min_secs = 1.0,
-        .min_secs_cache = 10.0 * 60 * 60,
+        .min_secs_cache = 1000.0 * 60 * 60,
         .seekable_cache = -1,
         .access_references = 1,
         .video_back_preroll = -1,