[Swan-dev] avoid two linear lookups

[D. Hugh Redelmeier]

commit e54650eb143644eaf0c9ed90c0488aa4ba5a86c9:

    pluto: print full name in 'ESP algorithm newest:' line
    
    and avoid two linear lookups

enum_short_name is not linear in any real sense.  It loops over the list 
of ranges, not within each range.

esp_transformid_names and auth_alg_names each have two ranges.

Avoiding several subroutine calls is more significant, but is unlikely to 
be consequential.

enum_short_name is linear in the length of the prefix because it calls 
strip_prefix, but that isn't a lookup.