* legoscia/remove-watchdog-vestiges/PR-1255/OTP-14112:
  Remove vestiges of watchdog support in heart

Hardware watchdog support was removed from heart in R13A, but there were
still some vestiges in the code and the documentation.

- Remove mentions of the HW_WD_DISABLE variable, as it's no longer used.
- Remove the HEART_BEAT_BOOT_DELAY variable, as it was only used for the
  hardware watchdog.

* gomoripeti/kernel/controlling_proc_badarg_doc/PR-1208/OTP-14022:
  controlling_process can return {error, badarg}

For gen_tcp, gen_udp and gen_sctp controlling_process/2 can return
badarg if erlang:port_connect/2 fails with badarg. This can easily
happen if the new owner is not alive but in some race condition also
when the socket is closed right before port_connect/2 (and after the
previous socket function)
This commit documents this behaviour.

In commit 3d70cee4034e, this text was changed to suggest that a list of Unix-specific permission bits would follow, but no such list was added. Let's revert back to the previous wording, so people won't look for a list that isn't there.

code:add_pathsa/1 reverts the list of directories when adding it at
the beginning of the code path. The command line option '-pa' behaves
in the same way. This is now documented.