Do not segfault when doing "ffplay -h"

Originally committed as revision 21640 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffplay.c

@@ -2600,7 +2600,7 @@ static const OptionDef options[] = {
     { "vst", OPT_INT | HAS_ARG | OPT_EXPERT, {(void*)&wanted_video_stream}, "select desired video stream", "stream_number" },
     { "sst", OPT_INT | HAS_ARG | OPT_EXPERT, {(void*)&wanted_subtitle_stream}, "select desired subtitle stream", "stream_number" },
     { "ss", HAS_ARG | OPT_FUNC2, {(void*)&opt_seek}, "seek to a given position in seconds", "pos" },
-    { "bytes", OPT_INT | HAS_ARG, {(void*)&seek_by_bytes}, "seek by bytes 0=off 1=on -1=auto" },
+    { "bytes", OPT_INT | HAS_ARG, {(void*)&seek_by_bytes}, "seek by bytes 0=off 1=on -1=auto", "val" },
     { "nodisp", OPT_BOOL, {(void*)&display_disable}, "disable graphical display" },
     { "f", HAS_ARG, {(void*)opt_format}, "force format", "fmt" },
     { "pix_fmt", HAS_ARG | OPT_EXPERT | OPT_VIDEO, {(void*)opt_frame_pix_fmt}, "set pixel format", "format" },