MFV r254070:
Merge vendor bugfix for ZFS test suite that triggers false positives.
Illumos ZFS issues:
3949 ztest fault injection should avoid resilvering devices 3950 ztest: deadman fires when we're doing a scan 3951 ztest hang when running dedup test 3952 ztest: ztest_reguid test and ztest_fault_inject don't place nice together