rustc: Add a lint for the obsolete crate-level link attribute
extra: impl IterBytes for uuid::Uuid
auto merge of #11091 : brson/rust/cratelinkattr, r=brson

This is set to *forbid* and prints a note explaining how to fix the problem.
auto merge of #11130 : olsonjeffery/rust/master, r=alexcrichton

So that `Uuid` can be used as the key in a `HashMap` or in a `HashSet`, etc

The only question I have about this is: Is endianness an issue, here? If so, what's the correct way to proceed?