test: fix common.mustCall length and name properties

Reassign `name` and `length` properties to the returned function to not
break code that relies on it.

test/common/index.js

@@ -387,10 +387,25 @@ function _mustCallInner(fn, criteria = 1, field) {
 
   mustCallChecks.push(context);
 
-  return function() {
+  const _return = function() { // eslint-disable-line func-style
     context.actual++;
     return fn.apply(this, arguments);
   };
+  Object.defineProperties(_return, {
+    name: {
+      value: fn.name,
+      writable: false,
+      enumerable: false,
+      configurable: true,
+    },
+    length: {
+      value: fn.length,
+      writable: false,
+      enumerable: false,
+      configurable: true,
+    },
+  });
+  return _return;
 }
 
 function hasMultiLocalhost() {