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.
Add library ctor and dtor for isc_os compilation unit which initializes
the numbers of the CPUs and also checks whether L1 cacheline size is
really 64 if the sysconf() call is available.
It was discovered that on some platforms (f.e. Alpine Linux with MUSL)
the result of isc_os_ncpus() call differ when called before and after we
drop privileges. This commit changes the isc_os_ncpus() call to cache
the result from the first call and thus always return the same value
during the runtime of the named. The first call to isc_os_ncpus() is
made as soon as possible on the library initalization.
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.
