Auto merge of #6451 - dwijnand:reify-DepFingerprint, r=alexcrichton
Auto merge of #6451 - dwijnand:reify-DepFingerprint, r=alexcrichton

Reify the DepFingerprint type

I'm very slightly concerned I might've incompatibly changed the serialise/deserialise code with respect to existing serialised data, so please double-check my work.

eminence/cargo,tshepang/cargo,rust-lang/cargo,tshepang/cargo,vojtechkral/cargo,tsurai/cargo,tsurai/cargo,rustyhorde/cargo,eminence/cargo,rust-lang/cargo,eminence/cargo,nipunn1313/cargo,eminence/cargo,nipunn1313/cargo,tshepang/cargo,tsurai/cargo,vojtechkral/cargo,nipunn1313/cargo,vojtechkral/cargo,tsurai/cargo,rust-lang/cargo,tshepang/cargo,tsurai/cargo,nipunn1313/cargo,rustyhorde/cargo,rust-lang/cargo,rustyhorde/cargo,vojtechkral/cargo,rustyhorde/cargo