ticket:9101: test tailoring in & around compact ranges of root primaries; fix an assertion; make nextWeight() a little simpler & more Java-friendly

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/markus@33803 251d0590-4201-4cf1-90de-194747b24ca1
ticket:9101: merge CollationTailoringDataBuilder code into CollationDataBuilder: better fit there, and there was almost nothing tailoring specific

git-svn-id: http://source.icu-project.org/repos/icu/icu/branches/markus@33807 251d0590-4201-4cf1-90de-194747b24ca1