Exploit mitigations applied by default are not documented

[Shnatsel]

There seems to be no documentation on exploit mitigations in Rust, specifically:

1. What exploit mitigations are supported?
2. What mitigations are enabled by default?
   1. Is that answer different if building with cargo instead of rustc directly?
   2. Does that vary by platform?
3. How to enable/disable specific mitigations?

This is relevant not only for security assessment, but also for performance comparison against other languages - both languages need to have the same exploit mitigations enabled for an apples-to-apples comparison.