Remove the libfuzzer max_len option which doesn't apply to other
fuzzing engines. Enforce the maximum length directly in the fuzz
targets. For the xml target, lower the maximum when expanding entities
to avoid timeout and OOM errors.
- Shorten timeouts
- Align options from Makefile and options files
- Add section headers to Makefile
- Skip invalid UTF-8 in regexp fuzzer
- Update regexp.dict
- Generate HTML seed corpus in correct format
This will be picked up OSS-Fuzz, limiting the maximum input size to
80 KB and hopefully avoiding timeouts. Some of the timeouts seem to be
related to our suboptimal handling of excessive entity expansion.
The new fuzzers support external entities and make this problem even
more prominent.
