Add len constants to certs.c
diff --git a/programs/ssl/dtls_client.c b/programs/ssl/dtls_client.c
index 4a19618..44d2175 100644
--- a/programs/ssl/dtls_client.c
+++ b/programs/ssl/dtls_client.c
@@ -130,7 +130,7 @@
 
 #if defined(POLARSSL_CERTS_C)
     ret = x509_crt_parse( &cacert, (const unsigned char *) test_ca_list,
-                          strlen( test_ca_list ) );
+                          test_ca_list_len );
 #else
     ret = 1;
     polarssl_printf("POLARSSL_CERTS_C not defined.");