make is_nonoverlapping private and remove num-traits dep from program-memory

[kevinheavey]

This function is only used here and in solana-bpf-loader program. When used here, it doesn't need num-traits. I have opened a PR in the Agave repo to copy the num-traits version into solana-bpf-loader program anza-xyz/agave#4888

The num-traits dep is causing pinocchio to copy-paste a significant amount of code.

Since the function is hidden this is not a breaking change.

[febo]

We could also add the missing unsafe markers – that way we can replicate the implementation from pinocchio here.

[kevinheavey]

We could also add the missing unsafe markers

Where?

[kevinheavey]

Oh guessing you mean these ones:

__This function is incorrectly missing an `unsafe` declaration.__

Let's leave those for another PR

[joncinque]

This makes sense to me, thanks for the contribution! Just a suggestion for the test.

And since this is a breaking change anyway, we can mark those functions unsafe as febo recommended in a separate PR, then release a new major version.

[joncinque]

Thanks!