build: add small-icu support for binary packages

Invokes the configure script used to build binary packages
(OSX pkg, binary tarballs, pkgsrc, MSI) with --download=all
--with-intl=small-icu.

Also makes PACKAGEMAKER customizable, because PackageMaker is not
necessarily installed in /Developer on OSX anymore.

Tested all binary packages on Windows, OSX, Linux and SmartOS.

Fixes #7676.

Reviewed-by: Steven R. Loomis <srl@icu-project.org>
Reviewed-by: Trevor Norris <trev.norris@gmail.com>