auto merge of #14952 : alexcrichton/rust/const-unsafe-pointers, r=brson

This does not yet change the compiler and libraries from `*T` to `*const T` as
it will require a snapshot to do so.

cc #7362

---

Note that the corresponding RFC, rust-lang/rfcs#68, has not yet been accepted. It was [discussed at the last meeting](https://github.com/rust-lang/rust/wiki/Meeting-weekly-2014-06-10#rfc-pr-68-unsafe-pointers-rename-t-to-const-t) and decided to be accepted, however. I figured I'd get started on the preliminary work for the RFC that will be required regardless.

Author: bors

syntax/rust.vim

@@ -30,8 +30,7 @@ syn keyword   rustKeyword     unsafe virtual while
 syn keyword   rustKeyword     use nextgroup=rustModPath skipwhite skipempty
 " FIXME: Scoped impl's name is also fallen in this category
 syn keyword   rustKeyword     mod trait struct enum type nextgroup=rustIdentifier skipwhite skipempty
-syn keyword   rustStorage     mut ref static
-syn keyword   rustObsoleteStorage const
+syn keyword   rustStorage     mut ref static const
 
 syn keyword   rustInvalidBareKeyword crate