Using the OpenSSL Dependency for Security Support and GDS

The GDS feature of Qt OPC UA as well as the security support for the Open62541 plugin requires the OpenSSL >= 1.1 headers and libraries.

If OpenSSL is not installed to a path that is searched by default, the location of the headers and libraries must be passed to the build process.

For example, if OpenSSL has been installed to /opt/openssl, the locations must be passed as follows:

 -DOPENSSL_ROOT_DIR=/opt/openssl/

The security capabilities of the Open62541 plugin and the GDS feature will be automatically disabled if OpenSSL is not detected during configuration.