am 84d92c71: (-s ours) am 615c9ab0: (-s ours) Upgrading libpng to 1.2.46 to fix a few vulnerabilities. DO NOT MERGE

* commit '84d92c718ab9f48faec0f640747c4b6f7a995607':
  Upgrading libpng to 1.2.46 to fix a few vulnerabilities. DO NOT MERGE