CVE-2025-12106 - IPv6 address parsing: fix buffer overread on invalid input

socket: reject mismatched address family in get_addr_generic

Add a family check to prevent copying address data of the wrong type, which could cause buffer over-read when parsing routes or endpoints.

OpenVPN version 2.7_alpha1 through 2.7_rc1 are affected. This is fixed in version 2.7_rc2.