ticket:10222: (C) Update some plural test cases, add better error logging

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk@33933 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10255: add U_HAVE_ATOMIC define, whether <atomic> can be included or not.  Also zap some whitespace.

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk@33935 251d0590-4201-4cf1-90de-194747b24ca1