hg: jdk-updates/jdk12u: 8220495: Update GIFlib library to the 5.1.8

[sergey.bylokhov at oracle.com]

Changeset: b18c66ec638e
Author:    serb
Date:      2019-03-31 16:57 -0700
URL:       http://hg.openjdk.java.net/jdk-updates/jdk12u/rev/b18c66ec638e

8220495: Update GIFlib library to the 5.1.8
Reviewed-by: prr

! src/java.desktop/share/legal/giflib.md
! src/java.desktop/share/native/libsplashscreen/giflib/dgif_lib.c
! src/java.desktop/share/native/libsplashscreen/giflib/gif_hash.h
! src/java.desktop/share/native/libsplashscreen/giflib/gif_lib.h
! src/java.desktop/share/native/libsplashscreen/giflib/gif_lib_private.h
! src/java.desktop/share/native/libsplashscreen/giflib/gifalloc.c
! src/java.desktop/share/native/libsplashscreen/giflib/openbsd-reallocarray.c