Add mips64 toolchain mips64el-linux-android-4.9

Build instructions:

export AOSP=your-AOSP-path
export NDK=$AOSP/ndk
cd $NDK ; ./build/tools/dev-cleanup.sh
./build/tools/download-toolchain-sources.sh /tmp/ndk-$USER/src
./build/tools/gen-platforms.sh --minimal --dst-dir=$NDK --ndk-dir=$NDK --arch=mips64
./build/tools/build-gcc.sh /tmp/ndk-$USER/src $NDK mips64el-linux-android-4.9 --try-64
rm -rf $NDK/toolchains/mips64el-linux-android-4.9/prebuilt/linux-x86_64/sysroot
cp -a $NDK/toolchains/mips64el-linux-android-4.9/prebuilt/linux-x86_64/* \
  $AOSP/prebuilts/gcc/linux-x86_64/mips/mips64el-linux-android-4.9

Change-Id: I6bf7f1cf4241d1b0c088c9796e6dfbe058bf081e
213 files changed