editors/vim and job control

vim lets you (and plugins) start and stop processes using job_start and
job_stop. There is an issue: stopping does not work, see for example
https://github.com/lervag/vimtex/issues/1032
in the case of the vimtex plugin. This is because the function
mch_signal_job in vim's src/os_unix.c first checks whether the process
to kill is group leader:

#ifdef HAVE_GETPGID
if (job_pid == getpgid(job_pid))
job_pid = -job_pid;