RFR: 8328999: Update GIFlib to 5.2.2

[Alexander Zvegintsev]

On Fri, 26 Apr 2024 22:02:38 GMT, Phil Race <prr at openjdk.org> wrote:

>> Updating giflib, clientlibs tests are green on all platforms
>
> src/java.desktop/share/native/libsplashscreen/giflib/gif_hash.h line 40:
> 
>> 38: #include <unistd.h>
>> 39: #endif
>> 40: /** End JDK modifications to support building on Windows **/
> 
> Do we still need this ?

The GIFLIB version 5.2.2 adds the `ifndef` wrap, so it looks like our comment can be removed

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PR Review Comment: https://git.openjdk.org/jdk/pull/18985#discussion_r1583770021