fix 2 typos in installing prebuilt llvm
added /lumen when creating $XDG_DATA_HOME/llvm/lumen (MacOS)
use `wget` for linux as well to download prebuilt llvm
@@ -79,14 +79,14 @@ the usual default for this XDG variable.
mkdir -p $XDG_DATA_HOME/llvm/lumen
cd $XDG_DATA_HOME/llvm/lumen
- https://github.com/lumen/llvm-project/releases/download/lumen-12.0.0-dev_2020-08-04/clang+llvm-10.0.0-x86_64-linux-gnu.tar.gz
+ wget https://github.com/lumen/llvm-project/releases/download/lumen-12.0.0-dev_2020-08-04/clang+llvm-10.0.0-x86_64-linux-gnu.tar.gz
tar -xz --strip-components 1 -f clang+llvm-10.0.0-x86_64-linux-gnu.tar.gz
rm clang+llvm-10.0.0-x86_64-linux-gnu.tar.gz
cd -
###### MacOS
- mkdir -p $XDG_DATA_HOME/llvm
+ mkdir -p $XDG_DATA_HOME/llvm/lumen
cd $XDG_DATA_HOME/llvm/lumen
wget https://github.com/lumen/llvm-project/releases/download/lumen-12.0.0-dev_2020-08-04/clang+llvm-10.0.0-x86_64-apple-darwin19.5.0.tar.gz
tar -xzf clang+llvm-10.0.0-x86_64-apple-darwin19.5.0.tar.gz
