MFC r319800,r319806:

r319800:

Don't explicitly get the class to PART in gctl_test_helper.c

This will allow the tool to be used with arbitrary geom(4) classes, like GEOM.

Specify class=PART explicitly in the tester to keep existing behavior.

r319806:

Improve handling with system state

- Always unlink $cmd after exit via END block.
- The tests don't function well if kern.geom.debugflags != 0. Save debugflags,
then restore them at the end of the test.

MFC r319015:

Use calloc instead of malloc + memset

MFC r317290,r317291,r317292,r317293,r317294,r317295,r317304,r317306,r317307,r317308,r317309:

r317290:

Fix -Wimplicit-function-declaration compilation warning by moving libgeom.h
#include below the stdio.h #include.

gctl_dump(3) needs stdio.h, per reasoning noted in r317289.

PR: 218809

r317291:

Rename gctl.t to gctl_test.t and test.c to gctl_test_helper.c

This is being done to reduce ambiguity and to make the tests more portable
in the future to other locations in the source tree.

r317292:

gctl_test.t: use make to compile gctl_test_helper instead of calling cc directly

r317293:

gctl_test_helper: apply polish

- Staticize variables to fix warnings.
- Sprinkle asserts around for calls that can fail
- Apply style(9) for main(..) definition.
- ANSIify usage(..) definition.

r317294:

Bump WARNS to 6 per previous commits which fixed warnings

Tested with: clang (4.0), gcc (4.2.1, 6.3.0)

r317295:

The GPT class no longer exists; use the PART class instead

r317304:

gctl_test_helper: add diagnostic output for parse_retval(..)

This will help end-users better diagnose issues with the function.

r317306:

gctl_test.t: minor tweaks

- Declare $count with the `my` scope operator to permit `use strict`.
- Add `use strict`.
- Use `use warnings` instead of using `-w` in the shebang.
- Don't unlink $cmd when done (prevents unnecessary rebuilding).
- Improve the error message when running with insufficient permissions, e.g.,
non-root.

r317307:

Use verb=delete not verb=remove

The `remove` verb hasn't been present in geom_part*(4) for well
over a decade, if ever. I couldn't find any references to it in
^/stable/5 at least, which is around the timeframe that this test
was written.

r317308:

gctl_test.t: more tweaks to try and update the code and get it functional (again?)

- Make the logfile for $out be built off the basename for $cmd, instead of $cmd.
(r317292 broke this assumption).
- Rename $mntpt to $mntpt_prefix for clarity, as this variable is a prefix for
mountpoints.
- Reindent the umount directive block while here to match the rest of the code.

r317309:

gctl_test.t: improve error reporting with mdcfg and mount directives

If the commands had failed previously, it would press on and result in a
series of cascading failures. Fail early and continue on to the next case
instead of executing additional commands after a previously failed series
of steps.