/usr/lib/x86_64-linux-gnu/icu/Makefile.inc is in libicu-dev 55.1-7.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/icu/current/Makefile.inc
/usr/lib/x86_64-linux-gnu/icu/current/Makefile.inc