Move dtors for refcounted objects to protected access.

indra/llcorehttp/_httpopcancel.h

indra/llcorehttp/_httpoperation.h

indra/llcorehttp/_httpoprequest.h

indra/llcorehttp/_httpopsetget.h

indra/llcorehttp/_httpopsetpriority.h

indra/llcorehttp/_httpreplyqueue.h

indra/llcorehttp/_httprequestqueue.h

indra/llcorehttp/bufferarray.h

indra/llcorehttp/httpheaders.h

indra/llcorehttp/httpoptions.h

indra/llcorehttp/httpresponse.h