Enable building arm64 libraries and upgrade from VS 2015 to 2019#21

niyas-sait wants to merge 2 commits intomhils:mastermhils/libxml2-win-binaries:masterfrom

niyas-sait:upgrade_to_vs2019_with_arm64_buildniyas-sait/libxml2-win-binaries:upgrade_to_vs2019_with_arm64_buildCopy head branch name to clipboard