Test environment.1 needs to use probe-file in both branches

[Yehouda]

In tests/osicat.lisp, the test environment.1 call probe-file on what it got out of the environment, which returns a truename, and compare it to the result user-homedir-pathname, which returns an implementation-dependent pathname. That can faill for various reasons, for example if the result of user-homedir-pathname is a link. It needs to call probe-file on the result of user-homedir-pathname.