Clippy improvements (#408)

* clippy: Allow subsec_nanos usage for now.

The recommendation from clippy requires Rust 1.27, but we currently
support Rust 1.25 and later.

* Simplify ref pattern matches.

This was recommended by clippy.

lib/codegen/src/lib.rs

@@ -5,6 +5,8 @@
 #![cfg_attr(feature = "std", warn(unstable_features))]
 #![cfg_attr(feature = "clippy", plugin(clippy(conf_file = "../../clippy.toml")))]
 #![cfg_attr(feature="cargo-clippy", allow(
+// This requires Rust 1.27 or later.
+                duration_subsec,
 // Produces only a false positive:
                 while_let_loop,
 // Produces many false positives, but did produce some valid lints, now fixed:

lib/faerie/src/backend.rs

@@ -362,15 +362,15 @@ impl<'a> RelocSink for FaerieRelocSink<'a> {
         name: &ir::ExternalName,
         addend: Addend,
     ) {
-        let ref_name: String = match name {
+        let ref_name: String = match *name {
-            &ir::ExternalName::User { .. } => {
+            ir::ExternalName::User { .. } => {
                 if self.namespace.is_function(name) {
                     self.namespace.get_function_decl(name).name.clone()
                 } else {
                     self.namespace.get_data_decl(name).name.clone()
                 }
             }
-            &ir::ExternalName::LibCall(ref libcall) => {
+            ir::ExternalName::LibCall(ref libcall) => {
                 let sym = (self.libcall_names)(*libcall);
                 self.artifact
                     .declare(sym.clone(), faerie::Decl::FunctionImport)

lib/filetests/src/lib.rs

@@ -5,7 +5,11 @@
 
 #![deny(missing_docs, trivial_numeric_casts, unused_extern_crates)]
 #![warn(unused_import_braces, unstable_features)]
-#![cfg_attr(feature = "cargo-clippy", allow(type_complexity))]
+#![cfg_attr(feature = "cargo-clippy",
+    allow(
+          type_complexity,
+          // This requires Rust 1.27 or later.
+          duration_subsec))]
 #![cfg_attr(
     feature = "cargo-clippy",
     warn(