fix: loading libc++ on macOS Sonoma

script/prepare-llvm-macos.sh

@@ -35,7 +35,12 @@ $CP llvm/lib/clang/*/include/{std*,__std*,limits}.h stage1/include/clang
 # libSystem stub, includes libc
 cp $SDK/usr/lib/libSystem.tbd stage1/lib/libc
 # use for linking, use system libs for running
-gcp llvm/lib/lib{c++,c++abi,unwind}.dylib stage1/lib/libc
+for lib in lib{c++,c++abi,unwind}.dylib; do
+  gcp llvm/lib/$lib stage1/lib/libc
+  # make sure we search for the library in /usr/lib instead of the rpath, which should not contain `/usr/lib`
+  # and apparently since Sonoma does not do so implicitly either
+  install_name_tool -id /usr/lib/$lib stage1/lib/libc/$lib
+done
 echo -n " -DLLVM=ON -DLLVM_CONFIG=$PWD/llvm-host/bin/llvm-config" # manually point to `llvm-config` location
 echo -n " -DLEAN_STANDALONE=ON"
 # do not change C++ compiler; libc++ etc. being system libraries means there's no danger of conflicts,