bug#56973: :keymap in register-definition-prefixes in loaddefs

[Stefan Kangas]

Severity: minor

I see in ldefs-boot.el lines like:

    (register-definition-prefixes "gnus-sum" '(":keymap" "gnus-"))

The ":keymap" there is from definitions like:

    (define-keymap :keymap gnus-summary-mode-map
        ...)

I'm not sure what is the best fix, however.  Should such cases just be
changed to use `defvar-keymap', or should we add `define-keymap' to
`autoload-ignored-definitions'?