Properly link flecs library

engine/libs/flecs/examples/cpp/queries/find_entity/src/main.cpp

@@ -0,0 +1,30 @@
+#include <find_entity.h>
+#include <iostream>
+
+struct Position {
+    int x, y;
+};
+
+int main() {
+    flecs::world ecs;
+
+    ecs.entity("e1").set<Position>({10, 20});
+    ecs.entity("e2").set<Position>({20, 30});
+
+    // Create a simple query for component Position
+    flecs::query<Position> q = ecs.query<Position>();
+
+    // Find the entity for which Position.x is 20
+    flecs::entity e = q.find([](Position& p) {
+        return p.x == 20;
+    });
+
+    if (e) {
+        std::cout << "Found entity " << e.path() << std::endl;
+    } else {
+        std::cout << "No entity found" << std::endl;
+    }
+
+    // Output
+    //  Found entity ::e2
+}