bug#27747: 26.0.50; cl-defgeneric does not have an Edebug spec

[Gemini Lasswell <gazally@runbox.com>]

There is no Edebug spec for cl-defgeneric, which means that default
method implementations and methods defined using its :method keyword
can't be Edebugged.

To reproduce the problem, start with this bit of code in a buffer:

(cl-defgeneric my-say (obj)
  "Say something about OBJ."
  (message "See the %s!" obj))

(cl-defmethod my-say ((obj number))
  (message "See the number %s!" obj))

Then:

M-x edebug-all-defs RET
M-x eval-buffer RET
M-: (my-say "cat") RET

Result: the command completes without Edebug starting.
This works correctly:

M-: (my-say 3) RET