remove some dependencies on itertools

Cargo.lock

@@ -3738,7 +3738,6 @@ dependencies = [
 name = "rustc_macros"
 version = "0.1.0"
 dependencies = [
- "itertools 0.8.0",
  "proc-macro2 1.0.3",
  "quote 1.0.2",
  "syn 1.0.11",
@@ -3802,7 +3801,6 @@ name = "rustc_mir_build"
 version = "0.0.0"
 dependencies = [
  "arena",
- "itertools 0.8.0",
  "log",
  "rustc",
  "rustc_apfloat",

src/librustc_macros/Cargo.toml

@@ -12,4 +12,3 @@ synstructure = "0.12.1"
 syn = { version = "1", features = ["full"] }
 proc-macro2 = "1"
 quote = "1"
-itertools = "0.8"

src/librustc_macros/src/query.rs

@@ -1,4 +1,3 @@
-use itertools::Itertools;
 use proc_macro::TokenStream;
 use proc_macro2::{Delimiter, TokenTree};
 use quote::quote;
@@ -469,10 +468,7 @@ pub fn rustc_queries(input: TokenStream) -> TokenStream {
                 attributes.push(quote! { eval_always });
             };
 
-            let mut attribute_stream = quote! {};
-            for e in attributes.into_iter().intersperse(quote! {,}) {
-                attribute_stream.extend(e);
-            }
+            let attribute_stream = quote! {#(#attributes),*};
 
             // Add the query to the group
             group_stream.extend(quote! {

src/librustc_mir_build/Cargo.toml

@@ -11,7 +11,6 @@ doctest = false
 
 [dependencies]
 arena = { path = "../libarena" }
-itertools = "0.8"
 log = "0.4"
 rustc = { path = "../librustc" }
 rustc_apfloat = { path = "../librustc_apfloat" }