fuzz: Add option to merge input dir to test runner
Summary:
This is mainly useful for myself to merge pull requests like bitcoin-core/qa-assets#4 I thought it wouldn't hurt to share the code. Also remove the --disable-ccache from the docs to speed up builds when developing fuzzers.
Backport of core PR18300.
Depends on D8270.
Test Plan:
ninja bitcoin-fuzzers ./test/fuzz/test_runner.py <path_to_corpus> git clone https://github.com/Bitcoin-ABC/qa-assets.git ~/seeds ./test/fuzz/test_runner.py ~/seeds/fuzz_seed_corpus \ --m_dir=<path_to_corpus> \ -l DEBUG
Reviewers: #bitcoin_abc, PiRK
Reviewed By: PiRK
Differential Revision: https://reviews.bitcoinabc.org/D8271