static-build: disable symbols renaming for libicu

ICU symbol renaming was disabled in EE build by commit
https://github.com/tarantool/tarantool-ee/commit/f51346d682e3afd93592023d0dedfb1e45167c7a
("static-build: disable symbols renaming for libicu"), because EE build
exports ICU symbols so that they can be used by Lua modules. It isn't
necessary in CE build, but since we're planning to reuse the CE cmake
config in the EE repository, we should do that.

Needed for https://github.com/tarantool/tarantool-ee/issues/185

NO_DOC=no functional changes
NO_TEST=no functional changes
NO_CHANGELOG=no functional changes