Includes fixes for CVE-2018-12383 and CVE-2018-12385.
* gnu/packages/patches/icecat-CVE-2018-12383.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/patches/icecat-avoid-bundled-libraries.patch: Adapt to apply
cleanly to IceCat 60.
* gnu/packages/gnuzilla.scm (mozilla-patch): Update to fetch from
mozilla-esr60.
(icecat): Add selected changesets from upstream mozilla-esr60.
Mark H Weaver