Update

[ghstack-poisoned]

Author: GregoryComer

.ci/scripts/test_backend_linux.sh

@@ -31,7 +31,7 @@ if [[ "$FLOW" == *qualcomm* ]]; then
     PYTHON_EXECUTABLE=python bash .ci/scripts/setup-qnn-deps.sh
     PYTHON_EXECUTABLE=python bash .ci/scripts/build-qnn-sdk.sh
     QNN_X86_LIB_DIR=`realpath build-x86/lib/`
-    export LD_LIBRARY_PATH=$QNN_X86_LIB_DIR:$LD_LIBRARY_PATH
+    export LD_LIBRARY_PATH=$QNN_X86_LIB_DIR:${LD_LIBRARY_PATH:-}
 
     # TODO Get SDK root from install scripts
     EXTRA_BUILD_ARGS+=" -DEXECUTORCH_BUILD_QNN=ON -DQNN_SDK_ROOT=/tmp/qnn/2.28.0.241029"