Combine ICU libraries icu-i18n and icu-uc into a single dependency

Combine ICU libraries icu-i18n and icu-uc into a single dependency

Rather than probing for icu-i18n, icu-uc, and icudata libraries
separately, only probe for icu-i18n, and icu-uc, as direct dependencies
This avoids overlinking with icudata, and allows the package
to build even when ICU is not installed as a system library.

RN: Only use icu-i18n and icu-uc to express ICU dependency

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15623

Signed-off-by: Earl Chew <earl_chew@yahoo.com>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>