gnu: icecat: Label patches that have since been assigned CVEs.

Document that the following CVEs are fixed: CVE-2016-9893, CVE-2016-9895,
CVE-2016-9897, CVE-2016-9898, CVE-2016-9899, CVE-2016-9900, CVE-2016-9901,
CVE-2016-9902, CVE-2016-9904, and CVE-2016-9905.  Note that these are all of
the CVEs fixed in Firefox ESR 45.6.

* gnu/packages/gnuzilla.scm (icecat)[source]: Add comments to patches that
have since been assigned CVEs.