Merge "adb: don't cache failure to get features."

}

const std::optional<FeatureSet>& adb_get_feature_set(std::string* error) {

    static std::string cached_error [[clang::no_destroy]];

    static const std::optional<FeatureSet> features

            [[clang::no_destroy]] ([]() -> std::optional<FeatureSet> {

    static std::mutex feature_mutex [[clang::no_destroy]];

    static std::optional<FeatureSet> features [[clang::no_destroy]] GUARDED_BY(feature_mutex);

    std::lock_guard<std::mutex> lock(feature_mutex);

    if (!features) {

        std::string result;

                if (adb_query(format_host_command("features"), &result, &cached_error)) {

                    return StringToFeatureSet(result);

        std::string err;

        if (adb_query(format_host_command("features"), &result, &err)) {

            features = StringToFeatureSet(result);

        } else {

            if (error) {

                *error = err;

            }

        }

                return std::nullopt;

            }());

    if (!features && error) {

        *error = cached_error;

    }

    return features;

}