Fix AppRTCDemo and AppRTCDemoTest builds.
Fix AppRTCDemo and AppRTCDemoTest builds.

On fresh checkout AppRTCDemo and corresponding tests
fail to build because resource file R.java is not auto generated properly.
On existing tree R.java will be picked up from previous
build leftover at talk/examples/android/gen.
Build bots did not detect this break for some reason.

R=wzh@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/43749004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#8723}
git-svn-id: 917f5d3ca488f358c4d40eaec14422cf392ccec9@8723 4adac7df-926f-26a2-2b94-8c16560cd09d

TimothyGu/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,ShiftMediaProject/libilbc,TimothyGu/libilbc,TimothyGu/libilbc,TimothyGu/libilbc