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.
In this commit, the simple fuzzing tests for the isc_lex_gettoken() and
isc_lex_getmastertoken() functions have been added.
As part of this commit, the initialization has been moved from fuzz.h
constructor/destructor to LLVMFuzzerInitialize() in each fuzz test. The
main.c of no-fuzzing and AFL modes have been modified to run the
LLVMFuzzerInitialize() at the start of the main() function mimicking
the libfuzzer mode of operation.
