Fix Tramp tests towards *BSD
* test/lisp/net/tramp-tests.el (tramp-get-remote-gid): Declare. (tramp-test18-file-attributes): Check `file-ownership-preserved-p' only if possible. (tramp-test30-make-process): Modify test due to *BSD.
* test/lisp/net/tramp-tests.el (tramp-get-remote-gid): Declare. (tramp-test18-file-attributes): Check `file-ownership-preserved-p' only if possible. (tramp-test30-make-process): Modify test due to *BSD.