Improve XEmacs compatibility.

* net/tramp.el (tramp-autoload-file-name-handler):
Wrap `temporary-file-directory' by `symbol-value', it doesn't exist in XEmacs.
(tramp-read-passwd): Don't use `with-timeout-suspend' and
`with-timeout-unsuspend' if they don't exist, like in XEmacs.
(tramp-time-less-p, tramp-time-subtract): Remove functions.
(tramp-handle-file-newer-than-file-p, tramp-time-diff):
* net/ttramp-adb.el (tramp-adb-ls-output-time-less-p):
* net/ttramp-cache.el (tramp-get-file-property):
* net/ttramp-smb.el (tramp-smb-handle-insert-directory):
Use `time-less-p' and `time-subtract, respectively.
Fix typo in ChangeLog.