ncurses: switch to new mirror

ncurses: switch to new mirror

github.com/mirror/ncurses is not updated for over a year.
Switch to new mirror from Thomas Dickey (ncurses maintainer).

Sources are identical.

Updated upstream check regex by:
* changed dot to underscore as this repo is tagged like this
* added v prefix to not propose updates to some old tags
* removed third part to not propose updates to development snapshots

Signed-off-by: Peter Marko <peter.marko@siemens.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>