How to build:
git clone https://github.com/Mr-Bossman/bpi-f3-buildroot
cd bpi-f3-buildroot
git submodule update --init
cd buildroot
make BR2_EXTERNAL=$PWD/../ bananapi_f3_defconfig
make
sudo dd status=progress oflag=sync bs=4k if=output/images/sdcard.img of=/dev/sdX; sync