bug#18581: icecat fails to build on i686

[Mark H Weaver]

The icecat build on i686 broke with the last core-updates merge.
See:

  http://hydra.gnu.org/build/96557/log/tail-reload
  http://hydra.gnu.org/job/gnu/master/icecat-24.0.i686-linux

Some of the notable updates in that merge include:

  glibc-2.20
  gnutls-3.2.16
  libunistring-0.9.4
  libgc-7.4.2
  libffi-3.1

Here's a more complete list:

  http://hydra.gnu.org/eval/100725#tabs-new

     Mark