100l, the compression field in lcl extradata must be interpreted as

int8_t, not uint8_t to allow -1 for "no compression".
The original code worked, but only when char was signed.

Originally committed as revision 19056 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/lcldec.c

@@ -512,7 +512,7 @@ static av_cold int decode_init(AVCodecContext *avctx)
     }
 
     /* Detect compression method */
-    c->compression = avctx->extradata[5];
+    c->compression = (int8_t)avctx->extradata[5];
     switch (avctx->codec_id) {
     case CODEC_ID_MSZH:
         switch (c->compression) {