Add an option to test constant-flow with valgrind

Currently the new component in all.sh fails because
mbedtls_ssl_cf_memcpy_offset() is not actually constant flow - this is on
purpose to be able to verify that the new test works.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/library/version_features.c b/library/version_features.c
index de14a2f..cbf38dc 100644
--- a/library/version_features.c
+++ b/library/version_features.c
@@ -280,6 +280,9 @@
 #if defined(MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN)
     "MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN",
 #endif /* MBEDTLS_TEST_CONSTANT_FLOW_MEMSAN */
+#if defined(MBEDTLS_TEST_CONSTANT_FLOW_VALGRIND)
+    "MBEDTLS_TEST_CONSTANT_FLOW_VALGRIND",
+#endif /* MBEDTLS_TEST_CONSTANT_FLOW_VALGRIND */
 #if defined(MBEDTLS_TEST_NULL_ENTROPY)
     "MBEDTLS_TEST_NULL_ENTROPY",
 #endif /* MBEDTLS_TEST_NULL_ENTROPY */