ffmpeg: no hwaccel methods on Android

[tri@intel-atom-x5] ~/local/bin $ ./ffmpeg -hwaccels
ffmpeg version N-78313-g6632802 Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 4.9 (GCC) 20140827 (prerelease)
  configuration: --prefix=/Users/tri/code/tools/android-ndk-r10e/sources/ffmpeg/android/arm --cross-prefix=/Users/tri/code/tools/android-ndk-r10e/toolchains/arm-linux-androideabi-4.9/prebuild/darwin-x86_64/bin/arm-linux-androideabi- --target-os=linux --arch=arm --enable-cross-compile --sysroot=/Users/tri/code/tools/android-ndk-r10e/platforms/android-21/arch-arm/ --extra-cflags='-0s -fPIE -marm' --extra-ldflags='-pie'
  libavutil      55. 17.000 / 55. 17.100
  libavcodec     57. 24.101 / 57. 24.101
  libavformat    57. 24.100 / 57. 24.100
  libavfilter     6. 28.100 /  6. 28.100
  libswscale      4.  0.100 /  4.  0.100
  libswresample   2.  0.101 /  2.  0.101
Hardware acceleration methods:

[^ none listed]

BUILD CONFIGURATION:

NDK=$HOME/code/tools/android-ndk-r10e
SYSROOT=$NDK/platforms/android-21/arch-arm/
TOOLCHAIN=$NDK/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64
MY_CFLAGS="-Os -fPIE -marm -DANDROID -DHAVE_SYS_UIO_H=1 -fasm -fno-short-enums -fno-strict-aliasing -finline-limit=300 -mthumb -D__thumb__"
MY_LDFLAGS="-pie"

./configure \
    --enable-cross-compile \
    --target-os=linux \
    --arch=arm \
    --cross-prefix=$TOOLCHAIN/bin/arm-linux-androideabi- \
    --sysroot=$SYSROOT \
    --extra-cflags="$MY_CFLAGS" \
    --extra-ldflags="$MY_LDFLAGS" \
    --disable-doc \
    --disable-ffplay \
    --disable-ffserver \
    --enable-gpl \
    --enable-nonfree \
	--enable-pthreads \
	--enable-hwaccels \
	--enable-hwaccel=h264_vaapi \
	--enable-hwaccel=h264_dxva2 \
	--enable-hwaccel=mpeg4_vaapi \
    --enable-libx264 \
	--enable-demuxer=h264 \
	--enable-decoder=h264 \
	--enable-encoder=h264 \
	--enable-parser=h264 \
	--enable-muxer=mp4 \
	--enable-decoder=mpeg4 \
	--enable-encoder=mpeg4 \
	--enable-decoder=aac \
	--enable-encoder=aac \
	--enable-muxer=mp2 \
	--enable-decoder=mp2 \
	--enable-encoder=mp2 \
	--enable-decoders \
	--enable-encoders \
	--enable-parsers \
	--enable-muxers \
	--enable-bsfs \
	--enable-avformat \
	--enable-avcodec \
	--enable-avresample \
	--enable-zlib

make clean
make