mariadb-connector-c: make keg_only

[cho-m]

mariadb-connector-c changes:

• keg_only - to remove conflicts and allow installing at same time as mariadb. This imitates mysql-client.
• use zstd everywhere to align Linux/macOS dep tree and match mysql-client feature
• drop unused args (WITH_OPENSSL, OPENSSL_INCLUDE_DIR, COMPILATION_COMMENT)
• fix path of man pages
• add -DINSTALL_LIBDIR=#{lib} to simplify Linux RPATH (otherwise dependents will need extra RPATH to #{lib}/mariadb). For backwards compatibility, add symlinks for shared libs that users may have linked to.
• add -DWITH_MYSQLCOMPAT=ON to simplify dependent builds. Particularly helps avoid accidentally linking to static libmariadbclient.a since MariaDB does not provide libmariadbclient.{so,dylib} symlink and some formulae search for mariadbclient before mariadb.
• manually create mysql_config symlink to simplify dependent builds as some old formulae don't look for mariadb_config too.
• compress manpages for small reduction in disk size.

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Going to also experiment with switching formulae to MariaDB library given:

• MySQL is using C++20 features that complicate dependency tree. Particular makes things more troublesome for Ventura and older, which will make it trickier for unsupported older macOS due to LLVM dependency.
• MariaDB still works with macOS zlib whereas MySQL propagates brew zlib (due to -lz getting passed to dependents)
• MariaDB connector is significantly smaller to install (e.g. < 2MB vs 125MB) though this could be improved by removing extra binaries from mysql-client.

MariaDB libraries has gotten decent testing in other repositories, e.g. a lot of Linux distros (e.g. Arch, Debian, Fedora) switched many years ago due to worry about Oracle open-source support (though this never became a problem).

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The formulae that use DBD::mysql may still need a mysql-client dependency as v5 claims to use some features from that variant. Arch and Debian have kept DBD::mysql v4 to deal with this while Fedora added dependency for MySQL 8.0

This impacts:

• innotop
• percona-toolkit
• percona-xtrabackup

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