[Go] Updated the 'callback' and 'extend' examples to match the 'director' one.

After the documentation update on how to utilize the director feature with
commit @17b1c1c the 'callback' and 'extend' examples needed an update as well.

Examples/go/extend/example.h

@@ -44,7 +44,7 @@ public:
 	const Employee *get_item(int i) {
 		return list[i];
 	}
-	~EmployeeList() { 
+	~EmployeeList() {
 		std::vector<Employee*>::iterator i;
 		std::cout << "~EmployeeList, deleting " << list.size() << " employees." << std::endl;
 		for (i=list.begin(); i!=list.end(); i++) {