I'm less certain that these are unneeded because networking APIs seem to have more variation between platforms, but it's better to remove the cruft and then add back whatever headers $PLATFORM users complain about, than to not remove the cruft at all...
The Berne Convention says that the copyright year is moot, so instead of adding another year to each file as in previous years, I've removed the year altogether from the source code comments in libtransmission, gtk, qt, utils, daemon, and cli.
Juliusz's copyright notice in tr-dht and Johannes' copyright notice in tr-lpd have been left alone; it didn't seem appropriate to modify them.