ZTS: Tests using zhack may fail on FreeBSD

As described in #11854, zhack is occasionally segfaulting on FreeBSD. 
Debugging this is proving to be tricky. To avoid false positives in
the CI add entries for the tests that use zhack in zts-report to 
accept that they may occasionally fail on FreeBSD.

Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Issue #11854
Closes #11855

tests/test-runner/bin/zts-report.py.in

@@ -252,8 +252,15 @@ if sys.platform.startswith('freebsd'):
         'cli_root/zfs_share/zfs_share_concurrent_shares':
             ['FAIL', known_reason],
         'cli_root/zpool_import/zpool_import_012_pos': ['FAIL', known_reason],
+        'cli_root/zpool_import/zpool_import_features_001_pos':
+            ['FAIL', '11854'],
+        'cli_root/zpool_import/zpool_import_features_002_neg':
+            ['FAIL', '11854'],
+        'cli_root/zpool_import/zpool_import_features_003_pos':
+            ['FAIL', '11854'],
         'delegate/zfs_allow_003_pos': ['FAIL', known_reason],
         'inheritance/inherit_001_pos': ['FAIL', '11829'],
+        'pool_checkpoint/checkpoint_zhack_feat': ['FAIL', '11854'],
         'removal/removal_condense_export': ['FAIL', known_reason],
         'removal/removal_with_export': ['FAIL', known_reason],
         'resilver/resilver_restart_001': ['FAIL', known_reason],