avcodec/gifdec: Add av_log() to workaround gcc 4.2 miscompiling the code

It appears gcc forgets to increment the byte stream pointer at -O3
I was not able to spot a reason/excuse for it to do that. It
also disappears if the function isnt inlined.

This should fix the gif fate failures on open & free bsd

See: [FFmpeg-devel] [PATCH] gifdec: workaround old gcc 4.2 mis-compiling code
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/gifdec.c

@@ -406,7 +406,7 @@ static int gif_parse_next_image(GifState *s, AVFrame *frame)
         int code = bytestream2_get_byte(&s->gb);
         int ret;
 
-        av_dlog(s->avctx, "code=%02x '%c'\n", code, code);
+        av_log(s->avctx, AV_LOG_DEBUG, "code=%02x '%c'\n", code, code);
 
         switch (code) {
         case GIF_IMAGE_SEPARATOR: