icu: fix build-time segfault by backporting upstream fix

The icu bug http://bugs.icu-project.org/trac/ticket/11959

 also
hit me, but oddly enough only when running build build server via
Jenkins. This patch adds the upstream fix for the mentioned bug, so the
patch most likely can be removed at the next version bump.

Signed-off-by: Zoltan Gyarmati <mr.zoltan.gyarmati@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>