rq_cxl_tests.sh: don't silently timeout when /root/ndctl is missing

Fail fast and print an error message instead.

There's probably a dependency missing between --options but that's a
different question.

Signed-off-by: Marc Herbert <marc.herbert@intel.com>

scripts/rq_cxl_tests.sh

@@ -12,7 +12,10 @@ trap cleanup EXIT
 sleep 4
 echo "======= auto-running $0 ========" > /dev/kmsg
 
-cd /root/ndctl || exit
+cd /root/ndctl || {
+    printf '<0> FATAL: %s: no /root/ndctl directory' "$0" > /dev/kmsg
+    exit 1
+}
 
 rm -rf build
 meson setup build 2>/dev/kmsg