Update to the rustfmt in rust 1.28, which is now stable.

Also, rustfmt's --write-mode=check is now named --check.

lib/codegen/src/regalloc/reload.rs

@@ -166,7 +166,8 @@ impl<'a> Context<'a> {
                     if arg.affinity.is_stack() {
                         // An incoming register parameter was spilled. Replace the parameter value
                         // with a temporary register value that is immediately spilled.
-                        let reg = self.cur
+                        let reg = self
+                            .cur
                             .func
                             .dfg
                             .replace_ebb_param(arg.value, abi.value_type);
@@ -199,7 +200,8 @@ impl<'a> Context<'a> {
         self.cur.use_srcloc(inst);
 
         // Get the operand constraints for `inst` that we are trying to satisfy.
-        let constraints = self.encinfo
+        let constraints = self
+            .encinfo
             .operand_constraints(encoding)
             .expect("Missing instruction encoding");
 
@@ -276,7 +278,8 @@ impl<'a> Context<'a> {
         // Same thing for spilled call return values.
         let retvals = &defs[constraints.outs.len()..];
         if !retvals.is_empty() {
-            let sig = self.cur
+            let sig = self
+                .cur
                 .func
                 .dfg
                 .call_signature(inst)