API docs like ucurr.h should say that choice formats are no longer used. This will greatly simplify call sites that try to handle possible outputs. For example, see isChoiceFormat in source:icu/trunk/source/i18n/unicode/ucurr.h ucurr_getName().
http://www.unicode.org/reports/tr35/tr35-numbers.html#Currencies says "The choice attribute has been deprecated."
In Java, isChoiceFormat can be null. We should allow isChoiceFormat=NULL in C too.