Improve compatibility with C++ consumers

[ghost]

Motivation and Context

FreeBSD has zfsd, which serves a similar purpose as zed. This program is written in C++.
C++ is a little picky about silly things like not using keywords for names and string const correctness.

Description

Mostly changed things in headers to rename parameters from class to clazz and private to priv.
One struct had a member named private which has been renamed to priv, and that required touching some .c files.
Corrected the constness of the name parameter to zpool_label_disk.

How Has This Been Tested?

Ran through ZTS on FreeBSD.

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)
• Documentation (a change to man pages or other documentation)

Checklist:

• My code follows the ZFS on Linux 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.

[codecov]

Codecov Report

Merging #10409 into master will decrease coverage by 0.08%.
The diff coverage is 76.92%.

@@            Coverage Diff             @@
##           master   #10409      +/-   ##
==========================================
- Coverage   79.45%   79.37%   -0.09%     
==========================================
  Files         391      391              
  Lines      123625   123625              
==========================================
- Hits        98230    98131      -99     
- Misses      25395    25494      +99     

Flag	Coverage Δ
#kernel	79.97% <75.00%> (+0.05%)	⬆️
#user	65.58% <69.23%> (+0.17%)	⬆️

Impacted Files	Coverage Δ
include/sys/abd.h	100.00% <ø> (ø)
lib/libspl/include/assert.h	0.00% <0.00%> (ø)
module/os/linux/zfs/spa_stats.c	82.61% <71.42%> (ø)
include/sys/dsl_dataset.h	100.00% <100.00%> (ø)
include/sys/range_tree.h	87.50% <100.00%> (ø)
lib/libspl/include/umem.h	93.75% <100.00%> (ø)
lib/libzfs/os/linux/libzfs_pool_os.c	69.64% <100.00%> (ø)
cmd/zdb/zdb_il.c	30.86% <0.00%> (-24.08%)	⬇️
module/zcommon/zfs_fletcher.c	68.09% <0.00%> (-10.20%)	⬇️
module/zfs/vdev_indirect.c	74.66% <0.00%> (-10.00%)	⬇️
... and 64 more

---

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[lundman]

I have this commit lined up for a PR:

openzfsonosx/openzfs@26fb082

there's probably a fair bit of overlap.

[behlendorf]

This looks good to me. Let's just verify that this PR covers everything that in @lundman's commit.

[ghost]

• Fix a few more headers caught by @lundman

[lundman]

I replaced my commit with yours;

os/macos/libzfs_pool_os.c:215:1: error: conflicting types for 'zpool_label_disk'
zpool_label_disk(libzfs_handle_t *hdl, zpool_handle_t *zhp, char *name)

Updated lib/libzfs/os/macos/libzfs_pool_os.c - to add const.

All compiled - takes care of my needs, cheers.

[ghost]

That dang zpool_import_012 sure is stubborn :|