All patching should be in _preprocess_cmd. config_cmd should just run
configure and nothing else before it, otherwise $PATH is broken when it runs.
Also remove redundant settings to configure, _autoconf already sets them.
We leave explicit AR_FLAGS settings because the builtin rule uses ARFLAGS,
and so would leave AR_FLAGS unset otherwise.
Make sure it links to our libtinfo from our ncurses build.
Hardcode some basic terminal descriptions into our libtinfo.
Re-enable $HOME/.terminfo support to allow user customization.
Use unlikely terminfo-dir, to prevent accidentally using
differently-configured system databases.
