ticket:5186: Make DecimalFormat::operator== much more complete

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@35312 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10730: Just add tests verifying correct behavior for U in skeleton (C)

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk/source@35315 251d0590-4201-4cf1-90de-194747b24ca1