Fix bug#22891: wrong terminal width when a fringe width is zero.

Fix bug#22891: wrong terminal width when a fringe width is zero.

When either fringe width is zero, Emacs reserved one column for a
continuation glyph. Terminal windows does not take this into
account when the frame is resized.

* lisp/window.el (window-adjust-process-window-size): Use
`window-max-chars-per-line' instead of `window-body-width'.
* lisp/term.el (term-window-width): Remove function. (It does the
same as `window-max-chars-per-line' but without recent bug fixes.)
(term-mode): Use `window-max-chars-per-line' instead of
`term-window-width'.