git: openjdk/jdk8u-dev: 8209115: adjust libsplashscreen linux ppc64le builds for easier libpng update

[Martin Balao]

Changeset: 50069a8d
Author:    Martin Balao <mbalao at openjdk.org>
Date:      2023-09-19 01:36:16 +0000
URL:       https://git.openjdk.org/jdk8u-dev/commit/50069a8dbccf07fcd412ac394a33be0afc97257e

8209115: adjust libsplashscreen linux ppc64le builds for easier libpng update

Reviewed-by: andrew, phh
Backport-of: e4fdd0391733756f5b898371a66b38869d625c77

! jdk/make/lib/Awt2dLibraries.gmk
! jdk/src/share/native/sun/awt/libpng/pngpriv.h