Rename some name variables as ident.

It bugs me when variables of type `Ident` are called `name`. It leads to
silly things like `name.name`. `Ident` variables should be called
`ident`, and `name` should be used for variables of type `Symbol`.

This commit improves things by by doing `s/name/ident/` on a bunch of
`Ident` variables. Not all of them, but a decent chunk.

compiler/rustc_hir/src/hir.rs

@@ -3399,9 +3399,9 @@ pub struct BareFnTy<'hir> {
     pub abi: ExternAbi,
     pub generic_params: &'hir [GenericParam<'hir>],
     pub decl: &'hir FnDecl<'hir>,
-    // `Option` because bare fn parameter names are optional. We also end up
+    // `Option` because bare fn parameter idents are optional. We also end up
     // with `None` in some error cases, e.g. invalid parameter patterns.
-    pub param_names: &'hir [Option<Ident>],
+    pub param_idents: &'hir [Option<Ident>],
 }
 
 #[derive(Debug, Clone, Copy, HashStable_Generic)]