* gnu/build/icecat-extension.scm: New file with a MAKE-ICECAT-EXTENSION
procedure that makes sure the add-on directory is a symlink, so that Icecat
can normalize it into a package store path.
* gnu/local.mk (dist_patch_DATA): Register it, as well as new patches.
* gnu/packages/browser-extensions.scm (ublock-origin)[properties]: Store the
add-on ID so that it is accessible in MAKE-ICECAT-EXTENSION.
[arguments]: Use the add-on ID as root directory.
(ublock-origin/icecat): New procedure.
* gnu/packages/gnuzilla.scm (icecat-minimal)[arguments]: Rewrite the unused
'apply-guix-specific-patches' phase so that it applies the following two
patches.
[native-search-paths]: New field.
* gnu/packages/patches/icecat-compare-paths.patch: New patch that compares
add-on paths (which are package store paths) to detect package changes.
* gnu/packages/patches/icecat-use-system-wide-dir.patch: New patch that
replaces "/usr/lib/mozilla" (the system-wide directory for extensions and
native manifests) with "$ICECAT_SYSTEM_DIR".
