bug#55830: `byte-compile` drops doc string

[Mattias Engdegård]

A function with doc string and interactive spec:

(defun hello ()
  "my function"
  (interactive)
  (message "hello"))

Then:

(byte-compile 'hello)

results in the doc string being lost.
This probably happens in byte-compile--reify-function where the doc string and 
interactive spec are swapped around.

Shouldn't that function also deal with :documentation? What about declare forms?