get_byte may not return -1 on error, since it can lead to a negative backptr.

Originally committed as revision 4854 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/lzo.c

@@ -34,7 +34,7 @@ static inline int get_byte(LZOContext *c) {
     if (c->in < c->in_end)
         return *c->in++;
     c->error |= LZO_INPUT_DEPLETED;
-    return -1;
+    return 0;
 }
 
 /**