Set The Global Allocator

Rust allows us to choose any allocator we want as the global allocator that will be used for all our allocations. We are using the mimalloc allocator. We can set it as the global allocator by adding a couple lines to our fuzzer's main.rs above the main function.

#![allow(unused)]
fn main() {
use mimalloc::MiMalloc;

#[global_allocator]
static GLOBAL: MiMalloc = MiMalloc;
}

This lets us use a different allocator in our fuzzer than is being called by our target, so when the target malloc state gets corrupted we won't crash the fuzzer.