Properly link flecs library

engine/libs/flecs/test/custom_builds/c/meta/src/main.c

@@ -0,0 +1,15 @@
+#include <meta.h>
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *world = ecs_init_w_args(argc, argv);
+
+    ecs_entity_t s = ecs_struct_init(world, &(ecs_struct_desc_t){
+        .members = {
+            { .name = "x", .type = ecs_id(ecs_i32_t) },
+            { .name = "y", .type = ecs_id(ecs_i32_t) }
+        }
+    });
+    assert(s != 0);
+
+    return ecs_fini(world);
+}