If you will notice, 'make distclean' removes 'Makefile', as
it is re-created by configure.

I think this is a bit unusual.
It's been a while since I have been building many packages manually (and
I've worked with hundreds), and I can't really recall that many packages
actually remove the Makefile, even when there is a Makefile.in.

It would be ideal to keep the Makefile around if possible so that
'make distclean' would always work.  It is a bit annoying.