This commit converts the license handling to adhere to the REUSE
specification. It specifically:
1. Adds used licnses to LICENSES/ directory
2. Add "isc" template for adding the copyright boilerplate
3. Changes all source files to include copyright and SPDX license
header, this includes all the C sources, documentation, zone files,
configuration files. There are notes in the doc/dev/copyrights file
on how to add correct headers to the new files.
4. Handle the rest that can't be modified via .reuse/dep5 file. The
binary (or otherwise unmodifiable) files could have license places
next to them in <foo>.license file, but this would lead to cluttered
repository and most of the files handled in the .reuse/dep5 file are
system test files.
3535. [func] Add support for setting Differentiated Services Code
Point (DSCP) values in named. Most configuration
options which take a "port" option (e.g.,
listen-on, forwarders, also-notify, masters,
notify-source, etc) can now also take a "dscp"
option specifying a code point for use with
outgoing traffic, if supported by the underlying
OS. [RT #27596]
