OK I just refreshed the buildroot external here : https://github.com/flatmax/buildroot.rockchip
It should work now. I did a test build and run.
Here are some changes to your methodology above :
export localDir=`pwd`
git clone [email protected]:flatmax/buildroot.rockchip.git
git clone git://git.busybox.net/buildroot buildroot
cd buildroot
git checkout 58fc4b5085763cf1837cab22e98b0eaa7fefaac5
source $localDir/buildroot.rockchip/setup.rockPiS.sh $localDir/buildroot
make
If you have previously built in the buildroot directory run the following before you source and make above :
make distclean