Auto merge of rust-lang#2225 - sgrif:sg-doctest-link-args, r=alexcric…

…hton

It is entirely possible for a crate to have a build script that is simply
the equivalent to

```rustc
fn main() {
    println!("cargo:rustc-link-search=native=/some/path");
}
```

Without actually giving anything to link (for example, because the code
contains `#[link(name="foo")]`. In this case, we aren't actually passing
`-L` through when running doctests, even though they're passed when
compiling the main crate.

Fixes rust-lang#1592

0.7.0 release

auto merge of rust-lang#988 : Gekkio/cargo/zsh-run-normal-args, r=ale…

…xcrichton

Running a Rust program with some arguments such as files is a common use
case. The ZSH completion did not declare support for extra arguments to
"cargo run", so file completion was impossible. In practice pressing TAB
after writing "cargo run -- " gave no completion at all.

After this patch, cargo run can do "normal completion",
which in practice does file/directory completion. This works nicely
with "cargo run -- ".