Support EMMA_INSTRUMENT in both full and unbundled builds.

Bug: 6987838
- With this change, use "EMMA_INSTRUMENT=true" to enable emma in full or
  unbundled build.
- You don't need to add "LOCAL_STATIC_JAVA_LIBRARIES += emma" any more for
  unbundled apps.
- Now a single var LOCAL_EMMA_INSTRUMENT replaces the previous
  LOCAL_NO_EMMA_INSTRUMENT and LOCAL_NO_EMMA_COMPILE.
- By default, if EMMA_INSTRUMENT is true, emma is enabled for only
  non-test apps.
- A new global var EMMA_INSTRUMENT_STATIC. It enables EMMA_INSTRUMENT
  and builds emma into apk/jar as static library, instead of using emma
  as part of shared library core.jar.

Change-Id: I0aa219e83074879ececc159b5b07c39eb07ccc00