This will be the case in OpenWrt soon.
#include <openssl/rsa.h>
#include <openssl/pem.h>
#include <openssl/evp.h>
+#ifndef OPENSSL_NO_ENGINE
#include <openssl/engine.h>
+#endif
#ifdef HAVE_LZO
#include LZO1X_H
init_configuration(&config_tree);
+#ifndef OPENSSL_NO_ENGINE
ENGINE_load_builtin_engines();
ENGINE_register_all_complete();
+#endif
OpenSSL_add_all_algorithms();
EVP_cleanup();
ERR_free_strings();
+#ifndef OPENSSL_NO_ENGINE
ENGINE_cleanup();
+#endif
exit_configuration(&config_tree);
list_delete_list(cmdline_conf);