Make toolchain doesn't work for me

Hi, @xlab

I went to cd $GOPATH/src/github.com/golang-ui/nuklear/cmd/nk-android

Did: make toolchain

And got:

/build/tools/make_standalone_toolchain.py
--api=21 --install-dir=/home/r3mb0/GoMobile/src/github.com/golang-ui/nuklear/cmd/nk-android/toolchain
--arch=arm --stl libc++ make: /build/tools/make_standalone_toolchain.py: Command not found Makefile:9: recipe for target 'toolchain' failed make: *** [toolchain] Error 127