* lisp/net/tramp.el (tramp-autoload-file-name-handler): Load Tramp only if
`tramp-mode' is non-nil.
(tramp-unload-file-name-handlers): Unload also
`tramp-autoload-file-name-handler'.
* test/lisp/net/tramp-tests.el (tramp-test42-delay-load): Extend test.