lint: add lint for use of a `~[T]`.
lint: add lint for use of a `~[T]`.

This is useless at the moment (since pretty much every crate uses
`~[]`), but should help avoid regressions once completely removed from a
crate.

GrahamDennis/rand,huonw/rand,retep998/rand,arthurprs/rand,bhickey/rand,ebfull/rand,shepmaster/rand,achanda/rand,bluss/rand,waynenilsen/rand