Add av_uninit macro to variable to avoid false positive warning:

libavcodec/eatgv.c: In function ‘tgv_decode_frame’:
libavcodec/eatgv.c:66: warning: ‘offset’ may be used uninitialized in this function

Originally committed as revision 17154 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/eatgv.c

@@ -63,7 +63,7 @@ static av_cold int tgv_decode_init(AVCodecContext *avctx){
  */
 static int unpack(const uint8_t *src, const uint8_t *src_end, unsigned char *dst, int width, int height) {
     unsigned char *dst_end = dst + width*height;
-    int size,size1,size2,offset,run;
+    int size, size1, size2, av_uninit(offset), run;
     unsigned char *dst_start = dst;
 
     if (src[0] & 0x01)