TERM=dumb / emacs

The readline / bash bug described in <comint: long lines truncated> may be fixed or not fixed. In any case, for some long time we will have to deal with programs where this bug is present. And it will be a bug only of some programs, not of whole system. So there must be a way in `comint.el' to revert to old `TERM=emacs' setting, and for some particular program being run, not globally. So checking for (and (boundp 'system-uses-terminfo) system-uses-terminfo) , like in emacs main cvs trunk, is *not* what should be copied.