Port System.Diagnostics.Process to OpenBSD

[sethjackson]

Port System.Diagnostics.Process to OpenBSD. Contributes to #124911.

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-system-diagnostics-process
See info in area-owners.md if you want to be subscribed.

[sethjackson]

@am11 FYI this is a WIP

[am11]

@sethjackson, with sethjackson#2, all test failures are gone:

am11@foo:~/system.diag.proc$ ./RunTests.sh --runtime-path ~/th/artifacts/bin/testhost/net11.0-openbsd-Debug-x64
...
  Discovering: System.Diagnostics.Process.Tests (method display = ClassAndMethod, method display options = None)
  Discovered:  System.Diagnostics.Process.Tests (found 382 of 464 test cases)
  Starting:    System.Diagnostics.Process.Tests (parallel test collections = on [5 threads], stop on fail = off)
.ProcessO    System.Diagnostics.Tests.ProcessStartInfoTests.ShellExecute_Nano_Fails_Start [SKIP]
      Condition(s) not met: "IsWindowsNanoServer"
OpenBSD
    System.Diagnostics.Tests.ProcessTests.TestBasePriorityOnUnix [SKIP]
      Condition(s) not met: "IsPrivilegedProcess"
    System.Diagnostics.Tests.ProcessTests.TestPriorityClassUnix [SKIP]
      Condition(s) not met: "IsPrivilegedProcess"
    System.Diagnostics.Tests.ProcessTests.TestProcessRecycledPid [SKIP]
      Condition(s) not met: "IsStressModeEnabledAndRemoteExecutorSupported"
    System.Diagnostics.Tests.ProcessTests.TestCheckChildProcessUserAndGroupIdsElevated [SKIP]
      Condition(s) not met: "IsRemoteExecutorSupportedAndPrivilegedProcess"
    System.Diagnostics.Tests.ProcessOpenTests.Open_ProtectedProcess_ThrowsUnauthorizedAccessException [SKIP]
      Condition(s) not met: "IsWindows"
  Finished:    System.Diagnostics.Process.Tests
=== TEST EXECUTION SUMMARY ===
   System.Diagnostics.Process.Tests  Total: 598, Errors: 0, Failed: 0, Skipped: 6, Time: 745.677s
~/system.diag.proc

[sethjackson]

Awesome! Thanks! I merged it.

[am11]

@janvorli, @adamsitnik, @wfurt, some code is shared with BSD/FreeBSD, rest is mostly definitions and OpenBSD specific mechanisms (what it lacks and provided alternatives).

[am11]

Closed/reopened to kick the build again. WithPackages leg failed because of versioning.targets is missing OpenBSD which is now merged to main (CI merges main to branch before running build so this approach works).

[sethjackson]

Closed/reopened to kick the build again. WithPackages leg failed because of versioning.targets is missing OpenBSD which is now merged to main (CI merges main to branch before running build so this approach works).

I can also merge main if that is preferable.

[am11]

I can also merge main if that is preferable.

Yes, feel free. :)

[janvorli]

LGTM, thank you!