scripts: add clang and llvm for PGO (#45)

setup-tools.sh

@@ -2,7 +2,7 @@
 # tested on ubuntu 20.04 Docker image
 
 apt update
-apt install proxychains4 shadowsocks-libev vim wget git tmux make gcc time curl libreadline6-dev libsdl2-dev gcc-riscv64-linux-gnu openjdk-11-jre zlib1g-dev device-tree-compiler flex autoconf bison sqlite3 libsqlite3-dev zstd libzstd-dev
+apt install proxychains4 shadowsocks-libev vim wget git tmux make gcc clang llvm time curl libreadline6-dev libsdl2-dev gcc-riscv64-linux-gnu openjdk-11-jre zlib1g-dev device-tree-compiler flex autoconf bison sqlite3 libsqlite3-dev zstd libzstd-dev
 sh -c "curl -L https://github.com/com-lihaoyi/mill/releases/download/0.11.6/0.11.6 > /usr/local/bin/mill && chmod +x /usr/local/bin/mill"
 
 # We need to use Verilator 4.204+, so we install Verilator manually