curses ui: always initialize all curses_line fields

cchar_t can contain not only attr and chars fields, but also ext_color.
Initialize the whole structure to zero instead of enumerating fields.

Spotted by Coverity: CID 1399711

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Message-Id: <20190315130932.26094-1-samuel.thibault@ens-lyon.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/curses.c

@@ -75,9 +75,9 @@ static void curses_update(DisplayChangeListener *dcl,
             if (vga_to_curses[ch].chars[0]) {
                 curses_line[x] = vga_to_curses[ch];
             } else {
-                curses_line[x].chars[0] = ch;
-                curses_line[x].chars[1] = 0;
-                curses_line[x].attr = 0;
+                curses_line[x] = (cchar_t) {
+                    .chars[0] = ch,
+                };
             }
             curses_line[x].attr |= at;
         }