It will be required by ICU 61 anyway, see
https://ssl.icu-project.org/repos/icu/trunk/icu4c/readme.html#RecBuild

Change-Id: Ib7accd75a6e35932048d779cf7bf0a5a33f8ed0d
Reviewed-on: https://gerrit.libreoffice.org/46741Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>
(cherry picked from commit 8960ecc6)
Reviewed-on: https://gerrit.libreoffice.org/56680
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
(cherry picked from commit 8790243d)