Properly link flecs library

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

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+#include <override.h>
+#include <iostream>
+
+// Overriding makes it possible for a prefab instance to obtain a private copy
+// of an inherited component. To override a component the regular add operation
+// is used. The overridden component will be initialized with the value of the
+// inherited component.
+//
+// In some cases a prefab instance should always have a private copy of an 
+// inherited component. This can be achieved with an auto override which can be
+// added to a prefab. Components with an auto override are automatically 
+// overridden when the prefab is instantiated.
+
+struct Attack {
+    double value;
+};
+
+struct Defense {
+    double value;
+};
+
+struct Damage {
+    double value;
+};
+
+int main() {
+    flecs::world ecs;
+
+    // Attack and Damage are properties that can be shared across many 
+    // spaceships. This saves memory, and speeds up prefab creation as we don't
+    // have to copy the values of Attack and Defense to private components.
+    flecs::entity SpaceShip = ecs.prefab("SpaceShip")
+        .set<Attack>({ 75 })
+        .set<Defense>({ 100 });
+
+    // Damage is a property that is private to a spaceship, so add an auto
+    // override for it. This ensures that each prefab instance will have a
+    // private copy of the component.
+    SpaceShip.set_override<Damage>({ 0 });
+
+    // Create a prefab instance.
+    flecs::entity inst = ecs.entity("my_spaceship").is_a(SpaceShip);
+
+    // The entity will now have a private copy of the Damage component, but not
+    // of the Attack and Defense components. We can see this when we look at the
+    // type of the instance:
+    std::cout << inst.type().str() << "\n";
+
+    // Even though Attack was not automatically overridden, we can always 
+    // override it manually afterwards by adding it:
+    inst.add<Attack>();
+
+    // The Attack component now shows up in the entity type:
+    std::cout << inst.type().str() << "\n";
+
+    // We can get all components on the instance, regardless of whether they
+    // are overridden or not. Note that the overridden components (Attack and
+    // Damage) are initialized with the values from the prefab component:
+    const Attack *a = inst.get<Attack>();
+    const Defense *d = inst.get<Defense>();
+    const Damage *dmg = inst.get<Damage>();
+
+    std::cout << "attack: " << a->value << "\n";
+    std::cout << "defense: " << d->value << "\n";
+    std::cout << "damage: " << dmg->value << "\n";
+
+    // Output:
+    //  Damage, (Identifier,Name), (IsA,SpaceShip)
+    //  Attack, Damage, (Identifier,Name), (IsA,SpaceShip)
+    //  attack: 75
+    //  defense: 100
+    //  damage: 0
+}