Ignore "reserved" dynamic formats for --list=subformats

Dynamic formats that are ignored for
	./john --test --format=dynamic
and other commands should also be ignored for
	./john --list=subformats

There was an inconsistency about the "reserved" formats
(all formats > 5000 vs. all formats >= 5000).
This inconsistency has been removed.
Dynamic formats >= 5000 are reserved now.
These reserved dynamic formats can still be used, if specified exactly:
	./john --test --format=dynamic_9025