Use lambda in tramp-compat-* functions

Use lambda in tramp-compat-* functions

* lisp/net/tramp-compat.el (tramp-handle-temporary-file-directory):
Declare.
(tramp-compat-temporary-file-directory-function): Use function symbol.
(tramp-compat-file-attribute-type)
(tramp-compat-file-attribute-link-number)
(tramp-compat-file-attribute-user-id)
(tramp-compat-file-attribute-group-id)
(tramp-compat-file-attribute-modification-time)
(tramp-compat-file-attribute-size)
(tramp-compat-file-attribute-modes)
(tramp-compat-directory-name-p, tramp-compat-file-local-name)
(tramp-compat-file-name-quoted-p, tramp-compat-file-name-quote)
(tramp-compat-file-name-unquote, tramp-compat-exec-path)
(tramp-compat-time-equal-p, tramp-compat-flatten-tree):
Make them lambdas.