bug#3767: 23.0.94; Functions in password-cache should be autoloaded

[Stefan Monnier]

>> I was wondering why jabber.el didn't cache my password, even though I
>> set password-cache and password-cache-expiry correctly, and found the
>> reason: jabber.el checks whether the running Emacs is new enough to have
>> password-cache.el by (fboundp 'password-read), but this function is not
>> autoloaded.  The problem is masked if you use Gnus.
>> 
>> Thus I propose that at least `password-read' be autoloaded, possibly
>> others as well.

> I think jabber.el should use the NOERROR argument to `require':

>   (if (require 'password-cache nil t)
>       use-password-cache
>     do-alternative)

To provide yet another opinion, I'd personally favor


   (ignore-errors (require 'password-cache))
   or
   (require 'password-cache nil t)

followed later on by

   (if (fboundp 'password-read)
       ...
     ...)


-- Stefan