ticket:10048: Fix some compiler warnings in ICU4C.

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk@33444 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10048: Compiler warning cleanup.

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk@33445 251d0590-4201-4cf1-90de-194747b24ca1
ticket:9914: ICU4C DateIntervalFormat to handle 2 year vs. 4 year formats.

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk@33453 251d0590-4201-4cf1-90de-194747b24ca1
ticket:10042: Fix documentation for unum_formatXXX()

git-svn-id: http://source.icu-project.org/repos/icu/icu/trunk@33455 251d0590-4201-4cf1-90de-194747b24ca1