const MAX_BYTES_TO_HASH: usize = 64;
This is the maximum size we will hash at a time, when interning an
Allocation and its
InitMask. Note, we hash that amount of bytes twice: at the start, and at the end of a buffer.
Used when these two structures are large: we only partially hash the larger fields in that
situation. See the comment at the top of their respective
Hash impl for more details.