Avoid hitting some known minor tinyformat issues when fuzzing
strprintf(...). These can be removed when the issues have been resolved
upstreams :)

Note to reviewers: The %c and %* issues are also present for %<some
junk>c and %<some junk>*. That is why simply matching on "%c" or "%*" is
not enough. Note that the intentionally trivial skipping logic
overshoots somewhat (c[…]% is filtered in addition to %[…]c).

ninja bitcoin-fuzzers
./test/fuzz/test_runner.py <path_to_corpus>