depends: Prepend -target to staging to avoid clashes with old deps

Also, fix a few missed ARCHS -> CURRENT_ARCH
depends: add setuptools for build-side python
depends: add distutilscross for building host python modules
depends: add PIL dependency
depends: add PIL dependency, but don't build by default yet
depends: use distribute rather than setuptools. Thanks ulion
depends: fix pil include path, it's not guarded from system libzip
depends: python: fix urllib on darwin
fix copy-constructor of Buffer, which fixes xbmcvfs.read() (fixes #14183)
[osx/ios/atv2] - sync xcode projects to include Buffer.h