comctl32/datetime: Fix length passed to GetLocaleInfoW().

Fix fullday not being rendered when long date format is used.

Signed-off-by: Zhiyi Zhang <zzhang@codeweavers.com>
Signed-off-by: Nikolay Sivov <nsivov@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/comctl32/datetime.c

@@ -697,7 +697,7 @@ DATETIME_ReturnFieldWidth (const DATETIME_INFO *infoPtr, HDC hdc, int count, SHO
 		for (i = 0; i < max_count; i++)
 		{
 		    if(GetLocaleInfoW(LOCALE_USER_DEFAULT, lctype + i,
-			buffer, lstrlenW(buffer)))
+			buffer, ARRAY_SIZE(buffer)))
 		    {
 			GetTextExtentPoint32W(hdc, buffer, lstrlenW(buffer), &size);
 			if (size.cx > cx) cx = size.cx;