Link libxml2

I have a simple swift wrapper around libxml2. There is no problems on Darwin or Linux with system library approach: ```swift .systemLibrary( name: "CLibXML2", pkgConfig: "libxml-2.0", providers: [ .brew(["libxml2"]), .apt(["libxml2-dev"]) ] ), ``` I don't know how to properly link on Android. As I undesrtand libxml2 should be part of sdk.