Fix SSL certificate handling & minor printf format fixes

[dougnazar]

Always load CA certificates if available.

Use SSL_CTX_use_certificate_chain_file() to load our public certifcate to allow loading intermediate & root CAs.

Verify that certificate & private key match.

This allows us to present the full certificate chain during handshake with the intermediate & root CAs stored in either the CA file or certificate file or a combination thereof.

[dougnazar]

Noticed the following items while testing with testssl. With the correct options, can now achieve an A+ grade.

• Enforce server cipher order
• Disable renegotiation.

Plus a few fixes to support compiling in a separate build directory.

[sawolf]

All of these changes look good to me - thanks for the patches