NetworkManagement SocketTagger: Migrate QTagUid support to JNI.

* Instead of javaland trying to write commands to
   /proc/net/xt_qtaguid/ctrl
use the libcutils/qtaguid.c support via JNI.
* Get rid of tagToKernel() handled by qtaguid library.

Requires libcutils changes from c/132538/

Change-Id: I9de5b3fa4a596c56835024c6d376769a0eea7db1