Add missing config from test-ref-configs.pl

The sample configuration file config-no-entropy.h was not being tested.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/tests/scripts/test-ref-configs.pl b/tests/scripts/test-ref-configs.pl
index c6298d0..94fc335 100755
--- a/tests/scripts/test-ref-configs.pl
+++ b/tests/scripts/test-ref-configs.pl
@@ -61,6 +61,8 @@
     'config-mini-tls1_1.h' => {
         'compat' => '-m tls1_1 -f \'^DES-CBC3-SHA$\|^TLS-RSA-WITH-3DES-EDE-CBC-SHA$\'',
     },
+    'config-no-entropy.h' => {
+    },
     'config-suite-b.h' => {
         'compat' => "-m tls1_2 -f 'ECDHE-ECDSA.*AES.*GCM' -p mbedTLS",
     },