ENGINE_register_all_complete() will register all implementations of all

ENGINE_register_all_complete() will register all implementations of all
algorithms present in all loaded ENGINEs. The result is that if any of
those ENGINEs successfully initialises, and the ENGINE_TABLE_FLAG_NOINIT
flag isn't set, then they will always be used (and cached as defaults) in
preference to software implementations. Ie. accidental auto-detection of
acceleration hardware :-)

This change stops all implementations being automatically registered in
"openssl" sub-commands, so that the "setup_engine()" handler in apps.c
controls which ENGINEs are registered for use. A special case has been
added that will revert to this "auto-detect" logic, ie. if the "-engine"
switch is used as;
   -engine auto