Properly link flecs library

engine/libs/flecs/examples/c/relationships/basics/src/main.c

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+#include <basics.h>
+#include <stdio.h>
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *ecs = ecs_init_w_args(argc, argv);
+
+    ECS_TAG(ecs, Eats);
+
+    // Entity used for Grows relationship
+    ecs_entity_t grows = ecs_new_entity(ecs, "Grows");
+
+    // Relationship objects
+    ecs_entity_t apples = ecs_new_entity(ecs, "Apples");
+    ecs_entity_t pears = ecs_new_entity(ecs, "Pears");
+
+    // Create an entity with 3 relationships. Relationships are like regular components,
+    // but combine two types/identifiers into an (relationship, object) pair.
+    ecs_entity_t bob = ecs_new_entity(ecs, "Bob");
+    // Pairs can be constructed from a type and entity
+    ecs_add_pair(ecs, bob, Eats, apples);
+    ecs_add_pair(ecs, bob, Eats, pears);
+    // Pairs can also be constructed from two entity ids
+    ecs_add_pair(ecs, bob, grows, pears);
+
+    // Has can be used with relationships as well
+    printf("Bob eats apples? %d\n", ecs_has_pair(ecs, bob, Eats, apples));
+
+    // Wildcards can be used to match relationships
+    printf("Bob grows food? %d\n", ecs_has_pair(ecs, bob, grows, EcsWildcard));
+
+    // Print the type of the entity. Should output:
+    //   (Identifier,Name),(Eats,Apples),(Eats,Pears),(Grows,Pears)
+    char *type_str = ecs_type_str(ecs, ecs_get_type(ecs, bob));
+    printf("Bob's type: [%s]\n", type_str);
+    ecs_os_free(type_str);
+
+    // Get first target of relationship
+    printf("Bob eats %s\n", 
+        ecs_get_name(ecs, ecs_get_target(ecs, bob, Eats, 0)));
+
+    // Get second target of relationship
+    printf("Bob also eats %s\n", 
+        ecs_get_name(ecs, ecs_get_target(ecs, bob, Eats, 1)));
+
+    return ecs_fini(ecs);
+}