Revert "Revert "xbps-src: when all deps have been processed exit directly.""

This reverts commit ad79b8e7e28824ebd77966d02fc7107cc0fcd444.
xbps-src: for runtime deps (depends) do not resolve vpkgs.

...otherwise the following would happen:

	- foo depends on musl
	- musl is provided by cross-vpkg-dummy
	- musl is then detected as resolved and it's not built.