Fix compilation warnings in tramp-loaddefs.el

Fix compilation warnings in tramp-loaddefs.el

* lisp/files.el (file-name-quoted-p): Autoload because it's
referred to from tramp-loaddefs.
* lisp/net/tramp.el (defvar): Put the entire form into the
loaddefs file instead of eval-and-compile -- this fixes a
dependency problem when byte-compiling the loaddefs file.
(tramp-methods, tramp-default-method-alist)
(tramp-default-user-alist, tramp-default-host-alist)
(tramp-local-host-regexp, tramp-terminal-type)
(tramp-foreign-file-name-handler-alist): Autoload to avoid
compilation warnings.  Also put (require 'cl-lib) into the
loaddefs file for the same reason.
(tramp-ensure-dissected-file-name)
(tramp-set-completion-function)
(tramp-register-foreign-file-name-handler): Autoload.