Android: rename android_build_type gyp variable.

Following Chromium r187556 this variable has been renamed to
android_webview_build to better describe what it does.

Contributed by torne@chromium.org (https://webrtc-codereview.appspot.com/1195006/).
Review URL: https://webrtc-codereview.appspot.com/1214005

git-svn-id: http://webrtc.googlecode.com/svn/trunk/webrtc@3686 4adac7df-926f-26a2-2b94-8c16560cd09d
1 file changed