config: don't link libudev on FreeBSD
FreeBSD has a libudev shim in libudev-devd. If present, configure would
detect it and produce binaries linked against it, even though nothing
used it. That is surprising and unnecessary, so lets remove it.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <robn@despairlabs.com>
Closes #14669