ztest: Use fnvlist_* instead of VERIFYing nvlist_*

[ghost]

Motivation and Context

Simplify ztest by using fnvlist functions to verify success.

Description

Use fnvlist functions, add a missing wrapper for nvlist_lookup_nvlist_array()

How Has This Been Tested?

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Performance enhancement (non-breaking change which improves efficiency)
• Code cleanup (non-breaking change which makes code smaller or more readable)
• Breaking change (fix or feature that would cause existing functionality to change)
• Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the OpenZFS code style requirements.
• I have updated the documentation accordingly.
• I have read the contributing document.
• I have added tests to cover my changes.
• I have run the ZFS Test Suite with this change applied.
• All commit messages are properly formatted and contain Signed-off-by.

[ghost]

I guess I need to bump the libnvpair version like this?

--- a/lib/libnvpair/Makefile.am
+++ b/lib/libnvpair/Makefile.am
@@ -40,7 +40,7 @@ if !ASAN_ENABLED
 libnvpair_la_LDFLAGS += -Wl,-z,defs
 endif

-libnvpair_la_LDFLAGS += -version-info 3:0:0
+libnvpair_la_LDFLAGS += -version-info 3:0:1

 # Library ABI
 EXTRA_DIST = libnvpair.abi libnvpair.suppr

[behlendorf]

We'd need to bump the library version to 3:1:0 since you're adding a new function and update the libnvpair.abi file. Though in this case I don't think it would be worthwhile. Why don't we instead simply drop the fnvlist_lookup_nvlist_array change to avoid changing the library ABI at all.

[ghost]

• Avoid adding fnvlist_lookup_nvlist_array
• Rebase