bug#73853: 31.0.50; Should and-let* become a synonym for when-let*?

[Stefan Monnier]

>>>>   - I'd like to go ahead and install a patch marking when-let and if-let
>>>>     as obsolete, unless Michael is keen to be the one to do it as the
>>>>     initiator of the previous effort
[...]
> Done.

Beside the use of `make-obsolete` instead of putting the `obsolete`
inside `declare`, I see a more serious problem with this patch.
E.g.

    (defun my-foo () (when-let ((x (point))) (goto-char x)))

gives 2 warnings rather than one:

    In my-foo:
    foo.el:3:19: Warning: ‘when-let’ is an obsolete macro (as of 31.1); use
        ‘when-let*’ or ‘and-let*’ instead.
    foo.el:3:2: Warning: ‘if-let’ is an obsolete macro (as of 31.1); use 
‘if-let*’
        instead.


- Stefan