Properly link flecs library

engine/libs/flecs/examples/cpp/prefabs/nested_prefabs/src/main.cpp

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+#include <nested_prefabs.h>
+#include <iostream>
+
+// Nested prefabs make it possible to reuse an existing prefab inside another
+// prefab. An example of where this could be useful is a car with four wheels:
+// instead of defining four times what a wheel is a Car prefab can reference an 
+// existing Wheel prefab.
+//
+// Nested prefabs can be created by adding a child that is a variant (inherits 
+// from) another prefab. For more information on variants, see the variants
+// example.
+//
+// Instantiated children from a nested prefab still inherit from the original
+// prefab. The reason for this is that an instantiated child is an exact copy
+// of the prefab child, and the prefab child only has an IsA relationship to the
+// nested prefab.
+//
+// This example shows how auto overriding (see the auto override example) can be
+// used to give instantiated children from a nested prefab a private copy of an
+// inherited component.
+
+struct TirePressure {
+    double value;
+};
+
+int main() {
+    flecs::world ecs;
+
+    // Create a Wheel prefab, make sure each instantiated wheel has a private
+    // copy of the TirePressure component.
+    flecs::entity Wheel = ecs.prefab("Wheel")
+        .set_override<TirePressure>({ 32 });
+
+    // Create a Car prefab with four wheels. Note how we're using the scope
+    // method, which has the same effect as adding the (ChildOf, Car) pair.
+    flecs::entity Car = ecs.prefab("Car").scope([&]{
+        ecs.prefab("FrontLeft").is_a(Wheel);
+        ecs.prefab("FrontRight").is_a(Wheel);
+        ecs.prefab("BackLeft").is_a(Wheel);
+        ecs.prefab("BackRight").is_a(Wheel);
+    });
+
+    // Create a prefab instance.
+    flecs::entity inst = ecs.entity("my_car").is_a(Car);
+
+    // Lookup one of the wheels
+    flecs::entity inst_front_left = inst.lookup("FrontLeft");
+
+    // The type shows that the child has a private copy of the TirePressure
+    // component, and an IsA relationship to the Wheel prefab.
+    std::cout << "type: [" << inst_front_left.type().str() << "]\n";
+
+    // Get the TirePressure component & print its value
+    inst_front_left.get([](const TirePressure p) {
+        std::cout << "pressure: " << p.value << "\n";
+    });
+
+    // Output:
+    //  type: [TirePressure, (Identifier,Name), (ChildOf,my_car), (IsA,Wheel)]
+    //  pressure: 32
+}