RFR: 8364177: JDK fails to build due to undefined symbol in libpng on LoongArch64

[Phil Race]

On Mon, 28 Jul 2025 09:25:34 GMT, Ao Qi <aoqi at openjdk.org> wrote:

> After [JDK-8329004](https://bugs.openjdk.org/browse/JDK-8329004), the following code was added.
> 
> 
> #ifndef PNG_LOONGARCH_LSX_OPT
> # if defined(__loongarch_sx)
> # define PNG_LOONGARCH_LSX_OPT 1
> # else
> # define PNG_LOONGARCH_LSX_OPT 0
> # endif
> #endif
> 
> 
> Some compilers on LoongArch64 platforms enable `__loongarch_sx`, which causes `PNG_LOONGARCH_LSX_OPT` to be defined and an undefined error occurs. Refer to [JDK-8078245](https://bugs.openjdk.org/browse/JDK-8078245), add `-DPNG_LOONGARCH_LSX_OPT=0` to `LIBSPLASHSCREEN_CFLAGS` flags.

If PNG_LOONGARCH_LSX_OPT is set to 0 it disables all those extra fns
https://github.com/openjdk/jdk/pull/18964/files

So LGTM.

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Marked as reviewed by prr (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26501#pullrequestreview-3068524024