This document describes how libicuio was packaged for build2. In particular,
this understanding will be useful when upgrading to a new upstream version.
See ../README-DEV for general notes on ICU packaging.

Symlink the required upstream directories into libicuio/:

$ ln -s ../../upstream/icu4c/source/io libicuio

Fix the 'unable to find numeric literal operator' GCC 11 error:

$ cp libicuio/io/ufile.cpp libicuio
$ patch -p0 <libicuio/ufile.cpp.patch