ticket:9101: build root elements table: compact ordered list of root CEs

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/markus@33358 251d0590-4201-4cf1-90de-194747b24ca1
ticket:9101: root collation data generated for allkeys-6.3.0d2.txt version of the DUCET

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/markus@33365 251d0590-4201-4cf1-90de-194747b24ca1