strongswan: add additional PACKAGECONFIG flags

- Add aesni, charon, gmp, openssl, scep, stroke, swanctl, and
  systemd-charon.
- Organize the packageconfig list alphabetically.
- Update the default PACKAGECONFIG to match current defaults.
- If swanctl is enabled, use strongswan-swanctl.service instead of
  strongswan.service.

Signed-off-by: Chris Patterson <pattersonc@ainfosec.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Joe MacDonald <joe_macdonald@mentor.com>