[RFA:] toplevel: Don't use makeinfo older than texinfo 4

[DJ Delorie]

If makeinfo doesn't exist on $PATH, does this end up printing an error
message each time you try to run $MAKEINFO ?

>   MAKEINFO = `if [ -f $$r/texinfo/makeinfo/Makefile ] ; \
>   	then echo $$r/texinfo/makeinfo/makeinfo ; \
> ! 	else if makeinfo --version \
> ! 		  | grep 'texinfo[^0-9]*[123][^0-9]' >/dev/null 2>&1; \
> !         then echo $$s/missing makeinfo; else echo makeinfo; fi; fi`