Add clang 18 support (#9)

https://releases.llvm.org/18.1.0/tools/clang/docs/ReleaseNotes.html

Author: XuJiandong

standalone-contract/scripts/find_clang

@@ -7,14 +7,15 @@ if [[ -n "${CLANG}" ]]; then
   exit 0
 fi
 
-CANDIDATES=("clang" "clang-16" "clang-17")
+CANDIDATES=("clang" "clang-16" "clang-17" "clang-18")
 
 BREW_PREFIX=$(brew --prefix 2> /dev/null)
 if [[ -n "${BREW_PREFIX}" ]]; then
   CANDIDATES+=(
     "${BREW_PREFIX}/opt/llvm/bin/clang"
     "${BREW_PREFIX}/opt/llvm@16/bin/clang"
     "${BREW_PREFIX}/opt/llvm@17/bin/clang"
+    "${BREW_PREFIX}/opt/llvm@18/bin/clang"
   )
 fi
 

workspace/scripts/find_clang

@@ -7,14 +7,15 @@ if [[ -n "${CLANG}" ]]; then
   exit 0
 fi
 
-CANDIDATES=("clang" "clang-16" "clang-17")
+CANDIDATES=("clang" "clang-16" "clang-17" "clang-18")
 
 BREW_PREFIX=$(brew --prefix 2> /dev/null)
 if [[ -n "${BREW_PREFIX}" ]]; then
   CANDIDATES+=(
     "${BREW_PREFIX}/opt/llvm/bin/clang"
     "${BREW_PREFIX}/opt/llvm@16/bin/clang"
     "${BREW_PREFIX}/opt/llvm@17/bin/clang"
+    "${BREW_PREFIX}/opt/llvm@18/bin/clang"
   )
 fi