This patch adds fuzzers built for the upstream cryptsetup project.
Initially, we try to fuzz LUKS2 on-disk format using various binary and
JSON header modification methods.
This produces basic coverage on on-disk header parsing code.
Fuzzers for other formats like LUKS1 will be added later.
Currently, we enable only binary fuzzer and plain JSON mutator with a
pre-generated corpus from previous experiments.
Changes based on Daniel Zatovic's work.
Signed-off-by: Milan Broz <gmazyland@gmail.com>