gnu: icecat: Add several security fixes.

* gnu/packages/patches/icecat-CVE-2015-4513-pt01.patch,
  gnu/packages/patches/icecat-CVE-2015-4513-pt02.patch,
  gnu/packages/patches/icecat-CVE-2015-4513-pt03.patch,
  gnu/packages/patches/icecat-CVE-2015-4513-pt04.patch,
  gnu/packages/patches/icecat-CVE-2015-4513-pt05.patch,
  gnu/packages/patches/icecat-CVE-2015-4513-pt06.patch,
  gnu/packages/patches/icecat-CVE-2015-4513-pt07.patch,
  gnu/packages/patches/icecat-CVE-2015-4513-pt08.patch,
  gnu/packages/patches/icecat-CVE-2015-4513-pt09.patch,
  gnu/packages/patches/icecat-CVE-2015-4513-pt10.patch,
  gnu/packages/patches/icecat-CVE-2015-4513-pt11.patch,
  gnu/packages/patches/icecat-CVE-2015-7188.patch,
  gnu/packages/patches/icecat-CVE-2015-7189.patch,
  gnu/packages/patches/icecat-CVE-2015-7193.patch,
  gnu/packages/patches/icecat-CVE-2015-7194.patch,
  gnu/packages/patches/icecat-CVE-2015-7196.patch,
  gnu/packages/patches/icecat-CVE-2015-7197.patch,
  gnu/packages/patches/icecat-CVE-2015-7198.patch,
  gnu/packages/patches/icecat-CVE-2015-7199.patch: New files.
* gnu-system.am (dist_patch_DATA): Add them.
* gnu/packages/gnuzilla.scm (icecat)[source]: Add patches.