Enable recursion for visit_ty in lint visitor

* The lint visitor's visit_ty method did not recurse, and had a
  reference to the now closed #10894
* The newly enabled recursion has only affected the `deprectated` lint
  which now detects uses of deprecated items in trait impls and
  function return types
* Renamed some references to `CowString` and `CowVec` to `Cow<str>` and
  `Cow<[T]>`, respectively, which appear outside of the crate which
  defines them
* Replaced a few instances of `InvariantType<T>` with
  `PhantomData<Cell<T>>`
* Disabled the `deprecated` lint in several places that
  reference/implement traits on deprecated items which will get cleaned
  up in the future
* Disabled the `exceeding_bitshifts` lint for
  compile-fail/huge-array-simple test so it doesn't shadow the expected
  error on 32bit systems
* Unfortunately, this means that if a library declares
  `#![deny(deprecated)]` and marks anything as deprecated, it will have
  to disable the lint for any uses of said item, e.g. any impl the now
  deprecated item

For any library that denies deprecated items but has deprecated items
of its own, this is a [breaking-change]

1 files changed, 3 insertions, 2 deletions

diff --git a/src/libstd/sys/windows/os_str.rs b/src/libstd/sys/windows/os_str.rs
index af94b56bf1f..ad1e6c4b0e7 100644
--- a/src/libstd/sys/windows/os_str.rs
+++ b/src/libstd/sys/windows/os_str.rs
@@ -11,9 +11,10 @@
 /// The underlying OsString/OsStr implementation on Windows is a
 /// wrapper around the "WTF-8" encoding; see the `wtf8` module for more.
 
+use borrow::Cow;
 use fmt::{self, Debug};
 use sys_common::wtf8::{Wtf8, Wtf8Buf};
-use string::{String, CowString};
+use string::String;
 use result::Result;
 use option::Option;
 use mem;
@@ -70,7 +71,7 @@ impl Slice {
         self.inner.as_str()
     }
 
-    pub fn to_string_lossy(&self) -> CowString {
+    pub fn to_string_lossy(&self) -> Cow<str> {
         self.inner.to_string_lossy()
     }