Rollup merge of #71470 - TyPR124:fix-doc-links, r=jonas-schievink

Fix doc links

This fixes a few doc links which were causing `cargo doc` to fail when using `--document-private-items --document-hidden-items` on libstd. Most of the fixes are just escaping '[' and ']' characters in doc comments, and one change actually fixes a doc link.

Author: Dylan-DPC

src/liballoc/collections/vec_deque.rs

@@ -73,7 +73,7 @@ pub struct VecDeque<T> {
 /// It produces the following sequence of matching slices:
 ///
 /// ([0 1], [a b])
-/// ([2], [c])
+/// (\[2\], \[c\])
 /// ([3 4], [d e])
 ///
 /// and the uneven remainder of either A or B is skipped.

src/liballoc/rc.rs

@@ -1024,7 +1024,7 @@ unsafe fn set_data_ptr<T: ?Sized, U>(mut ptr: *mut T, data: *mut U) -> *mut T {
 }
 
 impl<T> Rc<[T]> {
-    /// Copy elements from slice into newly allocated Rc<[T]>
+    /// Copy elements from slice into newly allocated Rc<\[T\]>
     ///
     /// Unsafe because the caller must either take ownership or bind `T: Copy`
     unsafe fn copy_from_slice(v: &[T]) -> Rc<[T]> {

src/liballoc/sync.rs

@@ -902,7 +902,7 @@ unsafe fn set_data_ptr<T: ?Sized, U>(mut ptr: *mut T, data: *mut U) -> *mut T {
 }
 
 impl<T> Arc<[T]> {
-    /// Copy elements from slice into newly allocated Arc<[T]>
+    /// Copy elements from slice into newly allocated Arc<\[T\]>
     ///
     /// Unsafe because the caller must either take ownership or bind `T: Copy`.
     unsafe fn copy_from_slice(v: &[T]) -> Arc<[T]> {

src/libcore/ffi.rs

@@ -282,7 +282,7 @@ impl<'a, 'f: 'a> DerefMut for VaList<'a, 'f> {
 mod sealed_trait {
     /// Trait which whitelists the allowed types to be used with [VaList::arg]
     ///
-    /// [VaList::va_arg]: struct.VaList.html#method.arg
+    /// [VaList::arg]: ../struct.VaList.html#method.arg
     #[unstable(
         feature = "c_variadic",
         reason = "the `c_variadic` feature has not been properly tested on \