Develop toolchain based on llvm for Cpu0 processor

BUILD steps:

Pre-install: https://github.com/Jonathan2251/lbd/README.rst

$ pwd

$ $HOME/git

$ git clone https://github.com/Jonathan2251/lbt

$ cd lbt/exlbt

$ bash build-cpu0-lbt.sh

$ bash newlib-cpu0.sh

CHECK step:

$ pwd

$ $HOME/git/lbt

$ bash check.sh