hg: jdk8u/jdk8u-dev/jaxp: 8230597: Update GIFlib library to the 5.2.1

[sgehwolf at redhat.com]

Changeset: 560093f31679
Author:    serb
Date:      2019-12-02 16:38 -0800
URL:       https://hg.openjdk.java.net/jdk8u/jdk8u-dev/jaxp/rev/560093f31679

8230597: Update GIFlib library to the 5.2.1
Reviewed-by: prr, psadhukhan, jdv

! THIRD_PARTY_README