Reorganize gyp for Android

BUG=1120
TEST=trybot, local test on xoom and nexus

Message:
It turned out the last CL can only build neon code that
caused problem on Xoom.

Description:
In order to support audo-cpu-detection, I split files into two gypi files, one
contains non-neon code, antoher one ONLY contains neon specific code, so I can
apply different flags to them. Also created two build targets for each of them

We build for linux as before.

Tested on xoom and nexus S.
Review URL: https://webrtc-codereview.appspot.com/930024

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3141 4adac7df-926f-26a2-2b94-8c16560cd09d
7 files changed