The poll code for kevent on OpenBSD and NetBSD had not been fixed
to work properly when disabling events in the scheduler poll-set.
Because they use ONESHOT the delete operation was built into the
trigger and thus a lot of code was not needed when doing oneshot,
however it is needed when doing non-oneshot.

Incorrect precidence rules made the driver never
deselect the given fds.

inet_drv adds some arcane #defines to get SCTP working, which may
end up disabling madvise(2) locally in that file, breaking the
build in the process.

This commit disables madvise(2) altogether on Solaris as it's
far simpler than undoing the define dance in erl_mmap.h.

Add enif_set_pid_undefined & enif_is_pid_undefined

* lukas/erts/fragment-dist-messages/OTP-13397/OTP-15610/OTP-15611/OTP-15612/OTP-15613:
  erts: Add debug dist obuf memory leak check
  win32: Fix ./otp_build debuginfo_win32
  Make ld.sh on windows print better error reason
  erts: Fix so that externals with creation 0 compare equal to all
  erts: Expand etp to look for free processes
  erts: Implement trapping while sending distr exit/down
  erts: Add ERL_NODE_BOOKKEEP to node tables refc
  erts: Refactor ErtsSendContext to be ErtsDSigSendContext
  erts: Add distr testcases for fragmentation
  erts: Make remote send of exit/2 trap
  erts: Implement fragmentation of distrubution messages
  erts: Expand distribution protocol documentation
  erts: Move reason in dist messages to payload
  erts: Remove a copy of distribution data payload
  erts: Yield later during process exit and allow free procs to run
  erts: Refactor rbt _yielding to use reductions
  erts: Limit binary printout for %.XT in erts_print