libvpx: Pull from upstream

source/libvpx/test/android/README

+Android.mk will build vpx unittests on android.
+1) Configure libvpx from the parent directory:
+./libvpx/configure --target=armv7-android-gcc --enable-external-build \
+  --enable-postproc --disable-install-srcs --enable-multi-res-encoding \
+  --enable-temporal-denoising --disable-unit-tests --disable-install-docs \
+  --disable-examples --disable-runtime-cpu-detect --sdk=$NDK
+
+2) From the parent directory, invoke ndk-build:
+NDK_PROJECT_PATH=. ndk-build APP_BUILD_SCRIPT=./libvpx/test/android/Android.mk \
+  APP_ABI=armeabi-v7a APP_PLATFORM=android-18 APP_OPTIM=release \
+  APP_STL=gnustl_static
+
+Note: Both adb and ndk-build are available prebuilt at:
+  https://chromium.googlesource.com/android_tools
+
+3) Run get_files.py to download the test files:
+python get_files.py -i /path/to/test-data.sha1 -o /path/to/put/files \
+  -u http://downloads.webmproject.org/test_data/libvpx
+
+4) Transfer files to device using adb. Ensure you have proper permissions for
+the target
+
+adb push /path/to/test_files /data/local/tmp
+adb push /path/to/built_libs /data/local/tmp
+
+NOTE: Built_libs defaults to parent_dir/libs/armeabi-v7a
+
+5) Run tests:
+adb shell
+(on device)
+cd /data/local/tmp
+LD_LIBRARY_PATH=. ./vpx_test