Be more precise about `mmap` and undefined behavior.
Be more precise about `mmap` and undefined behavior.

`mmap` doesn't *always* cause undefined behavior; it depends on the
details of how you use it.

graydon/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust