databases/rrdtool: Fix rrdtool resize on zfs FreeBSD 15

It appears that posix_fallocate in FreeBSD 15 now returns EOPNOTSUPP
instead of EINVAL.

See also:
https://lists.libvirt.org/archives/list/devel@lists.libvirt.org/thread/QZXFLC6E47UDM65GZAFDBZ2DJKIDT7N2/?sort=date
https://github.com/mariadb-corporation/galera/issues/685

PR: 296381