[Android][Crosswalk Mini] Remove ICU dependency for crosswalk

By using gyp flag use_icu_alternatives_on_android.
The changes in DEPS.xwalk will introduce the ICU dependency
removing efforts.

TODO(wang16):
1. The icu code is still contained in libxwalkcore.
   Only icudtl.dat is removed in apk right now.
   Next is to remove all the dependencies to icu target from gyps.
2. The icudtl.dat is still contained in the built packages
   including xwalk_core_library.tar.gz and xwalk_app_template.tar.gz.