fuzz: add a LLVMFuzzerInitialize() to all fuzzers

fuzz: add a LLVMFuzzerInitialize() to all fuzzers

To compile the AFL binaries, we need every fuzzer to have a consistent
set of functions. Some fuzzers require the initialize function, so all
the rest must have an empty one.

AFL binaires are handy for testing the fuzz results in a less magical
environment than libfuzzer/honggfuzz give you.

Signed-off-by: Douglas Bagnall <douglas.bagnall@catalyst.net.nz>
Reviewed-by: Jeremy Allison <jra@samba.org>