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.
The Windows support has been completely removed from the source tree
and BIND 9 now no longer supports native compilation on Windows.
We might consider reviewing mingw-w64 port if contributed by external
party, but no development efforts will be put into making BIND 9 compile
and run on Windows again.
BIND installation should be done by setting DESTDIR during "make
install" not by setting prefix via ./configure.
Make sure that installation with DESTDIR=<PATH> works by checking that
named binary and it's respective man page were installed and that
well-known BIND9 directories - and only them - are present in DESTDIR.
Also rename install path variable from BIND_INSTALL_PATH to
INSTALL_PATH to avoid namespace clash in stress tests which use
BIND_INSTALL_PATH variable to configure path to BIND9 binaries.
