Fix SSL off build, OCSPManager shouldn't be used when ssl = off

When building with SSL=off, latest 4.4.4 release doesn't compile with the following error:

src/mongo/db/db.cpp:340: error: undefined reference to 'mongo::OCSPManager::startThreadPool()'

src/mongo/util/net/ocsp/ocsp_manager.h:49: error: undefined reference to 'mongo::OCSPManager::OCSPManager()'

collect2: error: ld returned 1 exit status

scons: *** [build/opt/mongo/mongod] Error 1

scons: building terminated because of errors.

build/opt/mongo/mongod failed: Error 1

OCSPManager thread pool probably shouldn't be started when SSL is off, as this class is not compiled in the presence of such an option.

Also some info here: https://developer.mongodb.com/community/forums/t/failure-to-build-mongodb-4-4-4/100231

This is blocking Meteor build of MongoDB, as we do use a small binary without SSL for development easiness.

The last version it was working is : MONGODB_VERSION='4.2.8'

Original Summary

Ssl off build fails

Original Description

A build of MongoDB of install-core with --ssl=off does not work due to missing ifdefs to exclude SSL related code.