Initialize Qt Resource for Production Certificates

As this is a library, an initialization macro has to be called to make
sure the Qt resource is loaded and accesible.

src/cacertificates.cpp

@@ -33,6 +33,7 @@ static void initResourcesOutsideNamespace()
 #ifdef LIBFP311ONLINE_LOAD_DEVEL_CERT_RESOURCE
     Q_INIT_RESOURCE(devel_cert);
 #endif
+    Q_INIT_RESOURCE(prod_cert);
 }
 
 using namespace Fp311Online;