dialog: Override ncurses config script

Without the override, systemwide ncurses6-config can be found instead
of ncurses5-config from staging.

Signed-off-by: Maarten ter Huurne <maarten@treewalker.org>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/dialog/dialog.mk

@@ -17,4 +17,6 @@ ifneq ($(BR2_ENABLE_LOCALE),y)
 DIALOG_DEPENDENCIES += libiconv
 endif
 
+DIALOG_CONF_OPT += NCURSES_CONFIG=$(STAGING_DIR)/usr/bin/ncurses5-config
+
 $(eval $(autotools-package))