Update to rustfmt-preview (#348)

* Update to rustfmt-preview.

* Run "cargo fmt --all" with rustfmt 0.4.1.

rustfmt 0.4.1 is the latest release of rustfmt-preview available on the
stable channel.

* Fix a long line that rustfmt 0.4.1 can't handle.

* Remove unneeded commas left behind by rustfmt.

lib/codegen/src/binemit/shrink.rs

@@ -23,9 +23,7 @@ pub fn shrink_instructions(func: &mut Function, isa: &TargetIsa) {
 
                 // Pick the last encoding with constraints that are satisfied.
                 let best_enc = isa.legal_encodings(func, &func.dfg[inst], ctrl_type)
-                    .filter(|e| {
-                        encinfo.constraints[e.recipe()].satisfied(inst, &divert, &func)
-                    })
+                    .filter(|e| encinfo.constraints[e.recipe()].satisfied(inst, &divert, &func))
                     .min_by_key(|e| encinfo.bytes(*e))
                     .unwrap();
 
@@ -41,7 +39,6 @@ pub fn shrink_instructions(func: &mut Function, isa: &TargetIsa) {
                         encinfo.bytes(best_enc)
                     );
                 }
-
             }
             divert.apply(&func.dfg[inst]);
         }