libavcodec/lcldec: width and height should not be unsigned

Computations like col < width - 3 will not work with unsigned width=1

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 3eb4e28c26)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/lcldec.c

@@ -169,8 +169,8 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *frame,
     int row, col;
     unsigned char *encoded = avpkt->data, *outptr;
     uint8_t *y_out, *u_out, *v_out;
-    unsigned int width = avctx->width; // Real image width
-    unsigned int height = avctx->height; // Real image height
+    int width = avctx->width; // Real image width
+    int height = avctx->height; // Real image height
     unsigned int mszh_dlen;
     unsigned char yq, y1q, uq, vq;
     int uqvq, ret;