app_provider_load
int app_provider_load(OSSL_LIB_CTX *libctx, const char *provider_name);
if (!app_provider_load(NULL, "null")) {
return app_provider_load(app_get0_libctx(), opt_arg());
if (!app_provider_load(app_get0_libctx(), "legacy"))
if (!app_provider_load(app_get0_libctx(), "default"))