pam_krb5: Add missing patch

Include a portion of the patch that was missed in 813847e49e35.

Reported by: markj
Fixes: 813847e49e35

(cherry picked from commit bfa51318dee8afd9307f15e49a6a521938dccd06)
(cherry picked from commit d295e418ae7e60d87af6576ecdfad41a98d7442c)

Approved by: so
Security: FreeBSD-SA-23:09.pam_krb5
Security: CVE-2023-3326