Don't clear capability bounding set on capng_change_id

Don't clear capability bounding set on capng_change_id

The bounding set being empty will overpower the likes of su/sudo
and will make it impossible for any child processes to ever gain
additional privileges again.

Github: fixes OpenVPN/openvpn#220

Signed-off-by: Timo Rothenpieler <timo@rothenpieler.org>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20230118142428.162-1-timo@rothenpieler.org>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg26048.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>