fuzz: enable optimizations in other profiles
fuzz: enable optimizations in other profiles

The problem was that the fuzzer wasn't running with optimizations, which
means it was likely compiled in debug mode. So setting the optimization
level on the release profile won't do any good. Instead, we set it on
the debug and test profiles, which should cover it.

rust-lang-nursery/regex,rust-lang-nursery/regex,rust-lang/regex,rust-lang-nursery/regex,rust-lang-nursery/regex,rust-lang/regex,rust-lang-nursery/regex,rust-lang/regex,rust-lang/regex,rust-lang/regex