sync with TeXLive revision 44721

source/libs/libpng/ChangeLog

source/libs/libpng/README

source/libs/libpng/TLpatches/ChangeLog

source/libs/libpng/TLpatches/TL-Changes

source/libs/libpng/configure

source/libs/libpng/libpng-src/ANNOUNCE

source/libs/libpng/libpng-src/CHANGES

source/libs/libpng/libpng-src/CMakeLists.txt

source/libs/libpng/libpng-src/INSTALL

source/libs/libpng/libpng-src/LICENSE

source/libs/libpng/libpng-src/README

source/libs/libpng/libpng-src/configure.ac

source/libs/libpng/libpng-src/contrib/arm-neon/android-ndk.c

source/libs/libpng/libpng-src/contrib/examples/pngtopng.c

source/libs/libpng/libpng-src/contrib/gregbook/README

source/libs/libpng/libpng-src/contrib/gregbook/readpng.c

source/libs/libpng/libpng-src/contrib/gregbook/readpng2.c

source/libs/libpng/libpng-src/contrib/gregbook/readppm.c

source/libs/libpng/libpng-src/contrib/gregbook/rpng-win.c

source/libs/libpng/libpng-src/contrib/gregbook/rpng-x.c