* gnu/packages/gnuzilla.scm (icecat)[source]: Add more fixes from the
upstream mozilla-esr52 repository, plus a backported mitigation for
Spectre from Firefox 57.0.4.
* gnu/packages/patches/icecat-bug-1427870-spectre-mitigation.patch:
New file.
* gnu/local.mk (dist_patch_DATA): Add it.