Bug#820526: giflib: CVE-2016-3977: gif2rgb: heap buffer overflow

[Salvatore Bonaccorso]

Hi

As spotted by Marc Deslauriers, the patch was dropped again in the
5.1.4-0.4 reopening the issue. Looking at the source, the patch is not
applied to 5.1.4 upstream source.

Cc'ing Paolo four douple check/confirming.

Regards,
Salvatore