Finally, add a test recipe for the internal tests

Reviewed-by: NEmilia Käsper <emilia@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1789)

test/recipes/03-test_internal.t

+#! /usr/bin/env perl
+# Copyright 2015-2016 The OpenSSL Project Authors. All Rights Reserved.
+#
+# Licensed under the OpenSSL license (the "License").  You may not use
+# this file except in compliance with the License.  You can obtain a copy
+# in the file LICENSE in the source distribution or at
+# https://www.openssl.org/source/license.html
+
+use strict;
+use OpenSSL::Test qw/:DEFAULT bldtop_file/;
+use OpenSSL::Test::Utils;
+
+setup("test_internal");
+
+my %known_internal_tests =
+  ( mdc2_internal_test => !disabled("mdc2"),
+    poly1305_internal_test => !disabled("poly1305"),
+    modes_internal_test => 1,
+    asn1_internal_test => 1,
+    x509_internal_test => 1 );
+
+plan tests => scalar keys %known_internal_tests;
+
+foreach (keys %known_internal_tests) {
+ SKIP:
+    {
+	skip "Skipping $_, it's disabled in this configuration", 1
+	    unless $known_internal_tests{$_};
+	ok(run(test([$_])), "Running $_");
+    }
+}