How to build with actual ICU version (tested on debian 8.2):
wget http://download.icu-project.org/files/icu4c/56.1/icu4c-56_1-src.tgz tar xvzf icu4c-56_1-src.tgz cd icu/source ./configure --prefix=/opt/icu4c-php && make && make install
Add to php build config --with-icu-dir=/opt/icu4c-php