security/openvpn-devel: upgrade port to git commit d6ee27b4ff (2.7_rc2, 2025-11-17)

This commit brings the port to "openvpn 2.7_rc2"

Changes of interest for FreeBSD:

• IPv6 address parsing: fix buffer overread on invalid input (CVE-2025-12106)
• HMAC verification check: fix incorrect memcmp() call (CVE-2025-13086)
• even more type conversion related warnings have been fixed
• DCO FreeBSD improvements:

improving debug messages (verb 6)
implement client-side counter handling
repair --inactive (and document shortcomings)
repair handling of DCO disconnection notifications in --client mode

• improve cmocka unit test assert() handling
• PUSH_UPDATE server: fix reporting of client IPs in `status` output after pushing a new IPv4/IPv6 address to client
• AEAD cipher safety margins: fix calculation of AEAD blocks in use (old code would undercount blocks)
• fix invalid pointer creation / memory overread in tls_pre_decrypt
• deprecate `--opt-verify` (change into no-op + warning)

• additions by mandree@ --

Security: 50a0c266-c3ff-11f0-b513-0da7be77c170
Security: CVE-2025-12106
Security: 17a40d76-c3fd-11f0-b513-0da7be77c170
Security: CVE-2025-13086
MFH: 2025Q4