Rollup merge of #62532 - Mark-Simulacrum:syntax-print-cleanup, r=petrochenkov

Some more cleanups to syntax::print

All of these changes should be functionally equivalent to previous code.

Each commit mostly stands alone and this PR is easiest to review by-commit.

Author: Centril

src/librustc/hir/map/mod.rs

@@ -1212,10 +1212,8 @@ impl<'a> print::State<'a> {
             Node::Pat(a)          => self.print_pat(&a),
             Node::Arm(a)          => self.print_arm(&a),
             Node::Block(a)        => {
-                use syntax::print::pprust::PrintState;
-
                 // containing cbox, will be closed by print-block at }
-                self.cbox(print::indent_unit);
+                self.cbox(print::INDENT_UNIT);
                 // head-ibox, will be closed by print-block after {
                 self.ibox(0);
                 self.print_block(&a)