reorganize SoundPool and JetPlayer code.

Reorganize SoundPool and JetPlayer code to be ready for the
creation of libmedia_native.

Split SoundPool between libsoundpool (JNI) and libmedia(sound pool implementation).
Remove dependencies on nativehelper/jni.h from JetPlayer.

Change-Id: I130c6014173b714329929dd82c5dfb70b757a610
diff --git a/media/libmedia/JetPlayer.cpp b/media/libmedia/JetPlayer.cpp
index 7fa6bb7..52aee49 100644
--- a/media/libmedia/JetPlayer.cpp
+++ b/media/libmedia/JetPlayer.cpp
@@ -30,7 +30,7 @@
 static const S_EAS_LIB_CONFIG* pLibConfig = NULL;
 
 //-------------------------------------------------------------------------------------------------
-JetPlayer::JetPlayer(jobject javaJetPlayer, int maxTracks, int trackBufferSize) :
+JetPlayer::JetPlayer(void *javaJetPlayer, int maxTracks, int trackBufferSize) :
         mEventCallback(NULL),
         mJavaJetPlayerRef(javaJetPlayer),
         mTid(-1),