rollup merge of #22287: Ryman/purge_carthographers

This overlaps with #22276 (I left make check running overnight) but covers a number of additional cases and has a few rewrites where the clones are not even necessary.

This also implements `RandomAccessIterator` for `iter::Cloned`

cc @steveklabnik, you may want to glance at this before #22281 gets the bors treatment

src/test/bench/shootout-fasta.rs

@@ -132,7 +132,7 @@ fn run<W: Writer>(writer: &mut W) -> std::old_io::IoResult<()> {
                         ('t', 0.3015094502008)];
 
     try!(make_fasta(writer, ">ONE Homo sapiens alu\n",
-                    alu.as_bytes().iter().cycle().map(|c| *c), n * 2));
+                    alu.as_bytes().iter().cycle().cloned(), n * 2));
     try!(make_fasta(writer, ">TWO IUB ambiguity codes\n",
                     AAGen::new(rng, iub), n * 3));
     try!(make_fasta(writer, ">THREE Homo sapiens frequency\n",

src/test/bench/shootout-meteor.rs

@@ -202,7 +202,7 @@ fn filter_masks(masks: &mut Vec<Vec<Vec<u64>>>) {
     for i in 0..masks.len() {
         for j in 0..(*masks)[i].len() {
             masks[i][j] =
-                (*masks)[i][j].iter().map(|&m| m)
+                (*masks)[i][j].iter().cloned()
                 .filter(|&m| !is_board_unfeasible(m, masks))
                 .collect();
         }
@@ -270,7 +270,7 @@ fn handle_sol(raw_sol: &List<u64>, data: &mut Data) {
     // reverse order, i.e. the board rotated by half a turn.
     data.nb += 2;
     let sol1 = to_vec(raw_sol);
-    let sol2: Vec<u8> = sol1.iter().rev().map(|x| *x).collect();
+    let sol2: Vec<u8> = sol1.iter().rev().cloned().collect();
 
     if data.nb == 2 {
         data.min = sol1.clone();