ticket:9101: test & fix building from rules

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/markus@33769 251d0590-4201-4cf1-90de-194747b24ca1
ticket:9101: more tests, and fix adding extension CEs

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/markus@33776 251d0590-4201-4cf1-90de-194747b24ca1