Add libtpu configuration to cpp test script (#3957)

Author: steventk-g

test/cpp/run_tests.sh

@@ -47,6 +47,11 @@ if [[ "$TPUVM_MODE" != "1" ]]; then
   export XLA_EXPERIMENTAL
 fi
 
+# We need to configure the libtpu path to test on TPUVM
+if python -c "import libtpu" &> /dev/null; then
+  export TPU_LIBRARY_PATH=$(dirname $(python -c "import libtpu; print(libtpu.__file__)"))/libtpu.so
+fi
+
 rm -rf "$BUILDDIR"
 mkdir "$BUILDDIR" 2>/dev/null
 pushd "$BUILDDIR"