4l: TIFF stores short strings inside tag, do not interpret it is as an offset

Fixes issue 753
-This line, and those below, will be ignored--

M    libavcodec/tiff.c


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@16189 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/tiff.c

@@ -176,6 +176,11 @@ static int tiff_decode_tag(TiffContext *s, const uint8_t *start, const uint8_t *
             value = off;
             buf = NULL;
             break;
+        case TIFF_STRING:
+            if(count <= 4){
+                buf -= 4;
+                break;
+            }
         default:
             value = -1;
             buf = start + off;