Yellow squiggly lines begone!
Done automatically on .cpp files through `run-clang-tidy`, with manual corrections to the mistakes.
If an import is directly used, but is technically unnecessary since it's recursively imported by something else, it is *not* removed.
The tool doesn't touch .h files, so I did some of them by hand while fixing errors due to old recursive imports.
Not everything is removed, but the cleanup should be substantial enough.
Because this done on Linux, code that isn't used on it is mostly untouched.
(Hopefully no open PR is depending on these imports...)
macOS does not support `SO_PRIORITY` on sockets, but it does apparently
support configuring sockets with a priority flag via a parameter called
`SO_NET_SERVICE_TYPE`. It doesn't appear to be especially well
documented, but it seems to exist as far back as 10.11 (El Capitan).
This patch sets QoSSession to treat connections as
"responsive multimedia audio/video", which some docs appear to describe
as "low delay tolerant, low-medium, loss tolerant, elastic flow,
variable packet interval, rate and size".
SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.
