fuzz: Access fuzzing context in test_one_input #20232

After #20158, previous initialization behaviour and call patterns that relied on side-effects affecting our global g_chainman will no longer be possible. This means that 2 fuzz tests will break as we now need a local reference to a CChainState:

https://github.com/bitcoin/bitcoin/blob/49984b44cfcd3fd0cef16c8ce97197973afc3c04/src/test/fuzz/coins_view.cpp#L280-L285 https://github.com/bitcoin/bitcoin/blob/49984b44cfcd3fd0cef16c8ce97197973afc3c04/src/test/fuzz/load_external_block_file.cpp#L30

We do initialize a TestingSetup with InitializeFuzzingContext in some fuzz tests, but test_one_input has no way to access it.

TL;DR I'm wondering what's the best change to make the TestingSetup initialized in InitializeFuzzingContext accessible in test_one_input

Ping @practicalswift @MarcoFalke

Not sure what the question is. Arey you asking whether it is possible to have globals when fuzzing? Then yes, take a look at src/test/fuzz/process_message.cpp (g_setup)