Add arch-mips64 symlink

To build mips64el-linux-android-4.8
eg.
  ./build/tools/gen-platforms.sh --minimal --dst-dir=$NDK --ndk-dir=$NDK --overlay --arch=mips64
  ./build/tools/build-gcc.sh /tmp/ndk-$USER/src $NDK mips64el-linux-android-4.8 \
     --with-python=prebuilt --try-64

Change-Id: Ia1d4e12db2da18b1a20bcb00e754c23d8b5ba990
ToDo: Need to update platforms/android-9/arch-mips/src/crt*
1 file changed