This resulted in wrong values. The most prominent victim was the
directory creation mode, which was set to zero in some cases. For
details, see related blog post:
http://blog.gerhards.net/2009/10/another-note-on-hard-to-find-bugs.html

This replaces the improper bugfix from two commits ago with a proper one.

one-time write to the mode, then all works. However, if no such write
is done, the variable always remains zero. I have used the memory
debugger as well as shuffled the code around and used guard variables
nothing changed. The problem always moved with the changes I did. So
I now consider the one-time write a usable work-around, because it
definitely fixes the issue even though it does not explain why it
happens.

... thus causing them to be treated as TAG (this was a regression
introduced from the "rfc3164 strict" change in 4.5.0).

... part of the deprecation effort for v5

added tcp output rebinding option.

needs some more testing and doc