git: openjdk/jdk: 8305815: Update Libpng to 1.6.39

[Harshitha Onkar]

Changeset: 14874779
Author:    Harshitha Onkar <honkar at openjdk.org>
Date:      2023-05-03 19:39:12 +0000
URL:       https://git.openjdk.org/jdk/commit/14874779eeb9a279479c5aaddb40c056780d6152

8305815: Update Libpng to 1.6.39

Reviewed-by: prr

! 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/pnglibconf.h
! src/java.desktop/share/native/libsplashscreen/libpng/pngpriv.h
! src/java.desktop/share/native/libsplashscreen/libpng/pngrutil.c