git: openjdk/jdk17u-dev: 8316030: Update Libpng to 1.6.40

[Goetz Lindenmaier]

Changeset: 822c4962
Author:    Goetz Lindenmaier <goetz at openjdk.org>
Date:      2023-12-04 08:46:24 +0000
URL:       https://git.openjdk.org/jdk17u-dev/commit/822c49624b1e257a956de86ba4861fd7aa66534c

8316030: Update Libpng to 1.6.40

Backport-of: 158293d2517695f8c5eaca1b46ecf0f1f9f09691

! src/java.desktop/share/legal/libpng.md
! src/java.desktop/share/native/libsplashscreen/libpng/CHANGES
! src/java.desktop/share/native/libsplashscreen/libpng/LICENSE
! src/java.desktop/share/native/libsplashscreen/libpng/README
! src/java.desktop/share/native/libsplashscreen/libpng/png.c
! src/java.desktop/share/native/libsplashscreen/libpng/png.h
! src/java.desktop/share/native/libsplashscreen/libpng/pngconf.h
! src/java.desktop/share/native/libsplashscreen/libpng/pngget.c
! src/java.desktop/share/native/libsplashscreen/libpng/pnglibconf.h
! src/java.desktop/share/native/libsplashscreen/libpng/pngpriv.h
! src/java.desktop/share/native/libsplashscreen/libpng/pngset.c