Install llvm 18

Author: XuJiandong

Makefile

@@ -122,6 +122,7 @@ generate:
 prepare:
 	rustup target add riscv64imac-unknown-none-elf
 	cargo install --git https://github.com/nervosnetwork/ckb-standalone-debugger ckb-debugger --tag v0.118.0
+	wget https://apt.llvm.org/llvm.sh && chmod +x llvm.sh && sudo ./llvm.sh 18 && rm llvm.sh
 
 ci: build
 	ls -alht build/release