Feature request: allocate more time when minimizing long inputs

[Dor1s]

This was requested in https://bugs.chromium.org/p/chromium/issues/detail?id=997940, //cc @pwnall

I think we're currently using a constant timeout for minimization. Should we consider increasing it for large testcases and maybe decreasing for smaller ones?

[inferno-chromium]

Maybe just bump up for now. 180 feels too low. timeout = environment.get_value('LIBFUZZER_MINIMIZATION_TIMEOUT', 180)

[Dor1s]

I'm thinking for large testcases (e.g. more than 10KBs) we could try to allocate up to an hour? But don't want to spend that much for smaller things :/

[pwnall]

It would be nice if developers could override this from the console where we see the bugs. This saves you from having to come up with a threshold that works for all fuzzers, and lets you be judicious about spending compute -- when someone asks for a minimization, you know that the bug is being looked at.

[inferno-chromium]

A little bump up has been done in https://github.com/google/clusterfuzz/pull/1059

[Dor1s]

Sorry I still didn't get to it. Wanted to gather some data on how long we need to minimize depending on the size of the input, and didn't have time to run such experiments.

[inferno-chromium]

No worries, 3 min is crazy low anyway, so bumpup was necessary.