Cleaned up the build files for android_icu4j targets

The build targets for building android_icu47 targets were
in the icu4j/ file which is not following the standard
structure. This moves them into the android_icu4j/
file and also adds in targets for building on host to aid in
comparative testing of the repackaged JARs on both host and
Android. That should help us separate issues causes by
repackaging and issues caused by differences in behavior between
host and Android.
(cherry picked from commit 925333c86264c3e4986a5f8e0c3c096df29b578c)

Change-Id: I7d7ea7c9cd9a8c33377955f6b29372507fd162fb
2 files changed