Port trim_case() from AFL++

[andreafioraldi]

from @tokatoka

[andreafioraldi]

Testcase minimization has a low impact on fuzzing. It is ok to implement it, but not a priority now.

[tokatoka]

Closing because trim_case() seems to be useless.

[domenukk]

Don't we have tmin now which is basically that?

[tokatoka]

I think what they are trying to achieve is the same but afl-tmin and trim_case() are doing different things as far as I can tell