reproduce (this is a W=1 build):
        git remote add android-common https://android.googlesource.com/kernel/common
        git fetch --no-tags android-common android16-6.12
        git checkout 0e47a7391b3e2e57c4769f14a7be0ba7b56b10ca
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash mm/