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.
1 job for master in 58 minutes and 58 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #4991
test-all

00:58:58