bug#46918: 28.0.50; checkdoc fooled by qualified method

[Mauro Aranda]

Starting from emacs -Q:

1. Type the following in the *scratch* buffer
(cl-defmethod foo ((a (eql test)))
  "Return A."
  a)

(cl-defmethod foo :around ((a (eql test)))
  "Return A."
  a)

2. M-x checkdoc

3. See how checkdoc doesn't complain about the first method, but does
complain about the second method, with the following message:

Error message:
  All variables and subroutines might as well have a documentation string

which is wrong.