sudo: upgrade 1.9.13p3 -> 1.9.15p2

sudo: upgrade 1.9.13p3 -> 1.9.15p2

Upgrade 1.9.13p3 to 1.9.15p2 to fix bugs and CVEs

License-update: file removed upstream
Drop patch as issue fixed upstream.

Changelogs:
1.9.15p2: https://www.sudo.ws/releases/stable/#1.9.15p2
1.9.15p1: https://www.sudo.ws/releases/stable/#1.9.15p1
1.9.15:   https://www.sudo.ws/releases/stable/#1.9.15
1.9.14p3: https://www.sudo.ws/releases/stable/#1.9.14p3
1.9.14p2: https://www.sudo.ws/releases/stable/#1.9.14p2
1.9.14p1: https://www.sudo.ws/releases/stable/#1.9.14p1
1.9.14:   https://www.sudo.ws/releases/stable/#1.9.14

Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>