Does not compile with OpenSSL 3; issues related to deprecated libxml2 use

[ngie-eign]

The package fails to build against OpenSSL 3. Moreover, there are a variety of issues related to deprecated libxml2 use. Log originally came from https://pkg.bofh.network/data/MAIN-default-openssl3/2023-05-02_02h56m25s/logs/errors/xar-1.6.1_2.log . xar-1.6.1_2.log

[grahamperrin]

Cross-reference:

• FreeBSD bug 271193 – archivers/xar: does not compile/link against OpenSSL 3

See also:

• https://github.com/FreeBSD/freebsd-ports/commit/ebc92ce201aea980d653acebb91b6318cc191b93