kconfig/lxdialog: Add definitions for mininimum (re)size values

Commit c8dc68ad0fbd ("kconfig/lxdialog: support resize") added support
for resizing, but forgot to collect all hardcoded values at one single
place.

Also add a definition for the check for a minimum screen/window size
of 80x19.

[ ChangeLog v3:
  * Rename MENU_{HEIGTH,WIDTH}_MIN -> MENUBOX_{HEIGTH,WIDTH}_MIN
  ChangeLog v2:
  * Rename WIN_{HEIGTH,WIDTH}_MIN -> WINDOW_{HEIGTH,WIDTH}_MIN
  * Mention the check for a minimum screen/window size in the changelog
  * Add a comment above the block of new definitions ]

Signed-off-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Wang YanQing <udknight@gmail.com>
Tested-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
diff --git a/scripts/kconfig/lxdialog/util.c b/scripts/kconfig/lxdialog/util.c
index a0e97c2..78fe4e9 100644
--- a/scripts/kconfig/lxdialog/util.c
+++ b/scripts/kconfig/lxdialog/util.c
@@ -317,7 +317,7 @@
 	getyx(stdscr, saved_y, saved_x);
 
 	getmaxyx(stdscr, height, width);
-	if (height < 19 || width < 80) {
+	if (height < WINDOW_HEIGTH_MIN || width < WINDOW_WIDTH_MIN) {
 		endwin();
 		return -ERRDISPLAYTOOSMALL;
 	}