Update common_audio

Corresponds to upstream commit 524e9b043e7e86fd72353b987c9d5f6a1ebf83e1

Update notes:

 * Moved src/ to webrtc/ to easily diff against the third_party/webrtc
   in the chromium tree

 * ARM/NEON/MIPS support is not yet hooked up

 * Tests have not been copied

webrtc/modules/audio_processing/test/android/apmtest/default.properties

@@ -0,0 +1,11 @@
+# This file is automatically generated by Android Tools.
+# Do not modify this file -- YOUR CHANGES WILL BE ERASED!
+# 
+# This file must be checked in Version Control Systems.
+# 
+# To customize properties used by the Ant build system use,
+# "build.properties", and override values to adapt the script to your
+# project structure.
+
+# Project target.
+target=android-9