Update linpng submodule to fix a build problem under iOS

See https://github.com/wxWidgets/libpng/pull/1
This commit is contained in:
Vadim Zeitlin
2020-07-21 22:32:50 +02:00
parent 56177cb5a3
commit e77bba1a42

Submodule src/png updated: 46b17e804b...3ffeff7877