[libc++] Disable LLVM benchmarks in the Apple build

libcxx/utils/ci/apple-install-libcxx.sh

@@ -118,6 +118,7 @@ for arch in ${architectures}; do
             -GNinja \
             -DCMAKE_MAKE_PROGRAM="$(xcrun --sdk "${sdk}" --find ninja)" \
             -DLLVM_ENABLE_PROJECTS="libcxx;libcxxabi" \
+            -DLLVM_INCLUDE_BENCHMARKS=OFF \
             -C "${cache}" \
             -DCMAKE_INSTALL_PREFIX="${build_dir}/${arch}-install" \
             -DCMAKE_INSTALL_NAME_DIR="${install_name_dir}" \