ZTS: Add zts-report exceptions for FreeBSD

There are three tests we expect to fail only on FreeBSD.
* link_count never exits and eventually times out:
 - @amotin tells me this test is probably not applicable to us
 - Skip on FreeBSD
* userobj feature does not activate immediately after pool upgrade
 - low impact; we are aware of this issue
* removal does not appear to condense on export
 - low impact; we are aware of this issue

Additionally removal_with_zdb passes on FreeBSD, so it is moved to
"maybe".

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes #10093

tests/zfs-tests/tests/functional/link_count/link_count_001.ksh

@@ -49,6 +49,10 @@ log_assert "Verify file link count is zero on zfs"
 export ITERS=10
 export NUMFILES=10000
 
+if is_freebsd; then
+	log_unsupported "Not applicable on FreeBSD"
+fi
+
 # Detect and make sure this test must be executed on a multi-process system
 if ! is_mp; then
 	log_unsupported "This test requires a multi-processor system."