Correction for 20020921

[Philippe Blain]

>From Philippe Blain, Bordeaux, FRANCE.
My old computer: P133 - 8,4 Go - 32 Mo Red Hat Linux 7.0

To maintainers of 'ncurses'.(and to Mr Dickey)
Subject: Corrections for ncurses-5.2-20020921+

Here are some problems I found :

----------------------------------------------------------------------------
----
File : ncurses/base/lib_bkgd.c

Function : wbkgrnd()

    ...............
    else {
        NCURSES_CH_T wch = win->_line[y].text[x];
==>     RemAttr(wch, A_ALTCHARSET);
        win->_line[y].text[x] = _nc_render(win, wch);
    }
    ...............

Think that line is doing a visual bug when changing bkgrnd on a window
with line-drawing characters.
The graphics characters are changed in some ASCII chars.

Originaly, it was a  ==>     RemAttr(wch, ~A_ALTCHARSET); which did nothing.
That line was introduced from ncurses-5.1 to ncurses-5.2 with wide_chars
support.  In ncurses-5.1, it was (also false ?):
    ...............
 else
   win->_line[y].text[x] = _nc_render(win,
      (A_ALTCHARSET & AttrOf(win->_line[y].text[x])) |
      TextOf(win->_line[y].text[x]));
    ...............
And I don't see why removing the A_ALTCHARSET from graphics chars here ?.

----------------------------------------------------------------------------
- Philippe