[bug#67512] [PATCH 5/5] gnu: Add librewolf.

[Herman Rimm]

Hi Ian,

You can enable --with-system-png flag since libpng-apng >= 1.6.35. These
two icecat flags may be required for addons from gnuzilla.gnu.org:

  ;; Do not require addons in the global app or system directories to
  ;; be signed by Mozilla.
  "--with-unsigned-addon-scopes=app,system"
  "--allow-addon-sideload"

This icecat-minimal flag disables DRM:

  ;; The --disable-eme option is not available on aarch64.
  #$(if (target-aarch64?) "" "--disable-eme")

Librewolf should not link to addons.mozilla.org, using this build phase
from torbrowser:

  (add-before 'build 'fix-addons-placeholder
    (lambda _
      (substitute*
          "toolkit/locales/en-US/toolkit/about/aboutAddons.ftl"
        (("addons.mozilla.org") "gnuzilla.gnu.org"))))

Cheers,
Herman