Fix build with OPENSSL_NO_ENGINE

[fornwall]

• If you are contributing a new feature, is your work based off the develop branch?
• If you are contributing a bugfix, is your work based off the fixes branch?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully run make test with your changes locally?
• Have you signed the Eclipse Contributor Agreement, using the same email address as you used in your commits?
• Do each of your commits have a "Signed-off-by" line, with the correct email address? Use "git commit -s" to generate this line for you.

---

I haven't run make test as I only have a cross compile setup, where I've built openssl with no-engine passed to configure.

[ralight]

Lovely! Thanks very much.