rustc: Fix a number of stability lint holes

There are a number of holes that the stability lint did not previously cover,
including:

* Types
* Bounds on type parameters on functions and impls
* Where clauses
* Imports
* Patterns (structs and enums)

These holes have all been fixed by overriding the `visit_path` function on the
AST visitor instead of a few specialized cases. This change also necessitated a
few stability changes:

* The `collections::fmt` module is now stable (it was already supposed to be).
* The `thread_local::imp::Key` type is now stable (it was already supposed to
  be).
* The `std::rt::{begin_unwind, begin_unwind_fmt}` functions are now stable.
  These are required via the `panic!` macro.
* The `std::old_io::stdio::{println, println_args}` functions are now stable.
  These are required by the `print!` and `println!` macros.
* The `ops::{FnOnce, FnMut, Fn}` traits are now `#[stable]`. This is required to
  make bounds with these traits stable. Note that manual implementations of
  these traits are still gated by default, this stability only allows bounds
  such as `F: FnOnce()`.

Additionally, the compiler now has special logic to ignore its own generated
`__test` module for the `--test` harness in terms of stability.

Closes #8962
Closes #16360
Closes #20327

[breaking-change]

1 files changed, 3 insertions, 3 deletions

diff --git a/src/libcore/str/mod.rs b/src/libcore/str/mod.rs
index 013b7f27839..747152a8244 100644
--- a/src/libcore/str/mod.rs
+++ b/src/libcore/str/mod.rs
@@ -34,7 +34,7 @@ use ptr::PtrExt;
 use raw::{Repr, Slice};
 use result::Result::{self, Ok, Err};
 use slice::{self, SliceExt};
-use uint;
+use usize;
 
 macro_rules! delegate_iter {
     (exact $te:ty : $ti:ty) => {
@@ -783,7 +783,7 @@ impl TwoWaySearcher {
                 byteset: byteset,
 
                 position: 0,
-                memory: uint::MAX // Dummy value to signify that the period is long
+                memory: usize::MAX // Dummy value to signify that the period is long
             }
         }
     }
@@ -911,7 +911,7 @@ impl Searcher {
             Naive(NaiveSearcher::new())
         } else {
             let searcher = TwoWaySearcher::new(needle);
-            if searcher.memory == uint::MAX { // If the period is long
+            if searcher.memory == usize::MAX { // If the period is long
                 TwoWayLong(searcher)
             } else {
                 TwoWay(searcher)