Add libicuuc, libicui18n, libandroidicu, libpac to APEX

libandroidicu: Provides the stable C interface for other Android
components, except Apps. It's a stub of a subset of libicuuc and
libicui18n

libpac: It uses ICU4C C++ API, but has a stable C interface for
  libjni_pacprocessor. Thus, it should be moved into APEX.

Bug: 120659668
Bug: 121269980
Test: m droid
Test: art/build/apex/runtests.sh
Change-Id: I902c39b104a1678a046262e42efef07a60ee6558