Add test for issue 2644

Author: tspiteri

tests/source/issue-2644.rs

@@ -0,0 +1,11 @@
+// rustfmt-max_width: 80
+fn foo(e: Enum) {
+    match e {
+        Enum::Var {
+            element1,
+            element2,
+        } => {
+            return;
+        }
+    }
+}

tests/target/issue-2644.rs

@@ -0,0 +1,8 @@
+// rustfmt-max_width: 80
+fn foo(e: Enum) {
+    match e {
+        Enum::Var { element1, element2 } => {
+            return;
+        }
+    }
+}