Pass stereo gains as packed minifloat

This will allow (eventually) a greater dynamic range for gains.
However there are still a few remaining places in effects and mixer
that will also need to be changed in order to get the full benefit.

Also fixes a minor bug: was not checking for NaN in AudioTrack C++.

Change-Id: I63bce9e82e0a61546d8ff475fb94bcb700d99c96
diff --git a/media/mediaserver/Android.mk b/media/mediaserver/Android.mk
index d3e546a..5bc3f2f 100644
--- a/media/mediaserver/Android.mk
+++ b/media/mediaserver/Android.mk
@@ -35,7 +35,8 @@
     frameworks/av/services/medialog \
     frameworks/av/services/audioflinger \
     frameworks/av/services/audiopolicy \
-    frameworks/av/services/camera/libcameraservice
+    frameworks/av/services/camera/libcameraservice \
+    $(call include-path-for, audio-utils)
 
 LOCAL_MODULE:= mediaserver
 LOCAL_32_BIT_ONLY := true