Updating the vendored rkv crate to 0.5 will enable us to un-vendor the new-ordered-float crate <https://crates.io/crates/new-ordered-float>, as rkv 0.4 is the last crate in the tree that depends on it. Updating rkv will also update its dependency on the uuid crate from 0.5 to 0.6. Both those versions of uuid are already in tree, so that won't add (nor remove) a dependency. It would, however, enable us to remove uuid 0.5, if we also update geckodriver and webrender_bindings to depend on uuid 0.6.

MozReview-Commit-ID: 2Ogd6kqJ5MV Merge branch 'central' into vendor-rkv-0.5.1 MozReview-Commit-ID: 61OrQuVUYAU Bug 1500259 - update rkv to 0.5 and uuid to 0.6 Updating rkv to 0.5 enables us to un-vendor new-ordered-float, as rkv 0.4 is the last crate in the tree that depends on it. It also enables us to update uuid to 0.6 and un-vendor uuid 0.5, as the only crates left that depend on uuid 0.5 are internal (geckodriver and webrender_bindings). MozReview-Commit-ID: ICWICf56PHE

Pushed by myk@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/09a38fc0ac95 update rkv to 0.5 and uuid to 0.6 r=froydnj