add test for base and relative URLs with different schemes


git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@36101 72102866-910b-0410-8b05-ffd578937521
OSX compatibility when we are creating a URL relative to an incompatible base.


git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@36102 72102866-910b-0410-8b05-ffd578937521