Properly link flecs library

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

@@ -0,0 +1,13 @@
+#include <module.h>
+
+void MyModuleImport(ecs_world_t *world) {
+    ECS_MODULE(world, MyModule);
+}
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *world = ecs_init_w_args(argc, argv);
+
+    ECS_IMPORT(world, MyModule);
+
+    return ecs_fini(world);
+}