Actually, we cannot (easily) detect NANSI.SYS, so we don't enable optimizations by default.
You will have to `set TECO_TERM=nansi.sys` to enable optimizations.
Of course you can also still set the TERMCAP variable.

termcap was already doing it.
Perhaps termcap is meant to be the main Video TECO interface?

It's in termcap.h...

They were probably for compatibility on some obscure legacy UNIX,
that lacked the header for some strange reason.
(But then, why wouldn't you just define `struct pollfd` and poll()
in one of Video TECO's headers?)

* It's actually the time of running ./configure that will be used.
* On OpenWatcom, it does not seem to be possible to set variables
  based on external processes, so you will still have to update
  AUTO_DATE in teco.h when releasing for DOS.

The resulting config.h.in is similar to the one from the CVS repo.
However, I removed checks that apparently weren't referenced in the code base.
Also, I fixed the terminfo check. Previously, it was actually building against
termcap on my system. Terminfo should always be preferred.
Currently, it does not check against ncurses itself. If it turns out there are
systems with an ncurses pkg-config file, but without tinfo, we might have to check
for ncurses as well.

It adds both -Wall and -Wsign-compare, which turned out to be useful to
debug the DOS version.

The text files are added with DOS line-breaks.
Well, actually README.OLD is currently detected as a binary file,
so it won't.