Preserve backward compatibility in Tramp

Preserve backward compatibility in Tramp

* lisp/net/tramp-crypt.el (tramp-crypt-handle-lock-file)
(tramp-crypt-handle-unlock-file): Preserve backward compatibility.

* lisp/net/tramp-sh.el (tramp-sh-handle-write-region): Do not
create lock file twice.

* lisp/net/tramp.el (tramp-handle-make-lock-file-name): Move lock
file security check ...
(tramp-handle-lock-file): ... here.
(tramp-handle-unlock-file): Preserve backward compatibility.

* test/lisp/net/tramp-tests.el (lock-file-name-transforms)
(remote-file-name-inhibit-locks): Declare.
(tramp-allow-unsafe-temporary-files): Set to t.
(tramp-test37-make-auto-save-file-name)
(tramp-test38-find-backup-file-name): Move binding of
`tramp-allow-unsafe-temporary-files' up.
(tramp-test39-lock-file): Bind `tramp-allow-unsafe-temporary-files'.
Preserve backward compatibility.  Extend test.