l3build: Normalise out file paths for dependencies

This is important if a package is using a third-party dep and is allowing
tests to access the system tree. It's not needed if all dependencies are
supplied as deps: they will be 'here' in any case.


git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@5249 de43f980-851b-0410-b2f7-c40aca1f87e0
name correction

git-svn-id: http://www.latex-project.org/svnroot/experimental/trunk@5250 de43f980-851b-0410-b2f7-c40aca1f87e0