security/sudo: Update to 1.9.15

While here:

- Prevent combination of SSSD and GSSAPI_HEIMDAL because sssd port
  requires MIT kerberos and it will conflict with heimdal
- Removed SSSD_DEVEL option because sssd-devel port requires sudo and it
  creates a circular dependency
- Fix OPIE on FreeBSD versions after it was removed from base

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