Try fixing arm llama-runner jobs

Author: GregoryComer

.ci/scripts/setup-linux.sh

@@ -13,6 +13,12 @@ source "$(dirname "${BASH_SOURCE[0]}")/utils.sh"
 read -r BUILD_TOOL BUILD_MODE EDITABLE < <(parse_args "$@")
 echo "Build tool: $BUILD_TOOL, Mode: $BUILD_MODE"
 
+# Fix for libcxx version issues with PyTorch prebuilts.
+# Tracking in https://github.com/pytorch/executorch/issues/14679.
+if [ "$(uname -m)" != "aarch64" ]; then
+  conda install -c conda-forge libstdcxx-ng
+fi
+
 # As Linux job is running inside a Docker container, all of its dependencies
 # have already been installed, so we use PyTorch build from source here instead
 # of nightly. This allows CI to test against latest commits from PyTorch