vim-patch:8.1.0572: stopping a job does not work properly on OpenBSD

Problem:    Stopping a job does not work properly on OpenBSD.
Solution:   Do not use getpgid() to check the process group of the job
            processs ID, always pass the negative process ID to kill().
            (George Koehler, closes vim/vim#3656)
76ab4fd619

Ref: https://github.com/neovim/neovim/issues/9704
Ref: https://github.com/neovim/neovim/issues/10182#issuecomment-514450069
Closes https://github.com/neovim/neovim/pull/10660

test/functional/core/job_spec.lua

@@ -797,7 +797,7 @@ describe('jobs', function()
       eq(ppid, info.ppid)
     end
     -- Kill the root of the tree.
-    funcs.jobstop(j)
+    eq(1, funcs.jobstop(j))
     -- Assert that the children were killed.
     retry(nil, nil, function()
       for _, child_pid in ipairs(children) do