Add a test case for clone

Author: dianqk

tests/mir-opt/pre-codegen/no_inlined_clone.rs

@@ -0,0 +1,12 @@
+#![crate_type = "lib"]
+
+// EMIT_MIR no_inlined_clone.{impl#0}-clone.PreCodegen.after.mir
+
+// CHECK-LABEL: ::clone(
+// CHECK: inlined clone::impls::<impl Clone for {{.*}}>::clone
+// CHECK: return;
+
+#[derive(Clone)]
+struct Foo {
+    a: i32,
+}

tests/mir-opt/pre-codegen/no_inlined_clone.{impl#0}-clone.PreCodegen.after.mir

@@ -0,0 +1,17 @@
+// MIR for `<impl at $DIR/no_inlined_clone.rs:9:10: 9:15>::clone` after PreCodegen
+
+fn <impl at $DIR/no_inlined_clone.rs:9:10: 9:15>::clone(_1: &Foo) -> Foo {
+    debug self => _1;
+    let mut _0: Foo;
+    let mut _2: i32;
+    scope 1 (inlined clone::impls::<impl Clone for i32>::clone) {
+    }
+
+    bb0: {
+        StorageLive(_2);
+        _2 = ((*_1).0: i32);
+        _0 = Foo { a: move _2 };
+        StorageDead(_2);
+        return;
+    }
+}