librustc: Add a lint mode for unnecessary `copy` and remove a bunch of them.
librustc: Remove all uses of "copy".
librustc: Remove `copy` expressions from the language.
librustc: Remove all uses of the `Copy` bound.
test: Fix tests.
librustc: Change repeated vector expressions to use implicit copyability.
librustc: Remove the `Copy` bound from the language.
test: Fix tests.
libsyntax: Remove some multi-gigabyte clones that were preventing bootstrapping on Windows.
librustc: Remove some extra "copy" keywords that came in before this change merged.