MemoryErrors and failure to allocate memory

[devdanzin]

On machines with more cores, running multiple fusil instances in parallel often causes some of them to be unable to allocate memory and delete session directories.

Edit: also happens when running a single instance in a machine. When the fuzzer starts in this state, only a couple of Python modules have been found.

The failure to allocate memory can begin at the start of the instance, or develop after it's running for a while.

Investigate whether raising the memory limit alleviates the issue. Also consider detecting this state and bailing out.