Use @str instead of @~str in libsyntax and librustc. Fixes #5048.

This almost removes the StringRef wrapper, since all strings are
Equiv-alent now. Removes a lot of `/* bad */ copy *`'s, and converts
several things to be &'static str (the lint table and the intrinsics
table).

There are many instances of .to_managed(), unfortunately.

src/libsyntax/parse/common.rs

@@ -158,7 +158,7 @@ impl Parser {
             self.fatal(
                 fmt!(
                     "expected `%s`, found `%s`",
-                    *self.id_to_str(kw.to_ident()),
+                    self.id_to_str(kw.to_ident()),
                     self.this_token_to_str()
                 )
             );