ticket:10273: IBM i fixes

git-svn-id: http://source.icu-project.org/repos/icu/icu@34299 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10379: IBM i - make tests run without any special options, update readme

git-svn-id: http://source.icu-project.org/repos/icu/icu@34300 251d0590-4201-4cf1-90de-194747b24ca1