bug#64797: 30.0.50; advised alias -> "function is an alias for nil" in Help

[Michael Heerdegen]

Hello,

an example: `manual-entry' is an alias for `man'.  When now the alias is
advised, for example like

  (advice-add 'manual-entry :filter-return #'identity)

and you do C-h f manual-entry RET, the first line of the Help buffer
will say:

| manual-entry is an alias for ‘nil’, which is not defined.

which is obviously nonsense.

Seems that this regression in `help-fns--analyze-function' had been
introduced by

d30fde6b0cc "Avoid infloops in help-fns--analyze-function with aliases"
(Lars Ingebrigtsen <larsi@gnus.org> 2022-01-13)

I CC Mattias and Stefan you might be able to help.


TIA,

Michael.