mkid reference

Hi!

in src/tools/make_diff/ there is a reference:

"If I use mkid (from ftp.postgreSQL.org), I can do:"

There is no such thing on our download site, and I can't find what it
even was at one point.

Was this part of some other package, since removed?

And maybe even more interestnig -- is there a point to this whole
make_diff directory at all in these days of git? Or should we just
remove it rather than try to fix it?

-- 
 Magnus Hagander
 Me: https://www.hagander.net/
 Work: https://www.redpill-linpro.com/