settings put global ntp_server <server name>

/**
 * SNTP client config: The preferred NTP server. This setting overrides the static
 * config.xml configuration when present and valid.
 *
 * <p>The legacy form is the NTP server name as a string.
 * <p>Newer code should use the form: ntp://{server name}[:port] (the standard NTP port,
 * 123, is used if not specified).
 *
 * <p>The settings value can consist of a pipe ("|") delimited list of server names or
 * ntp:// URIs. When present, all server name / ntp:// URIs must be valid or the entire
 * setting value will be ignored and Android's xml config will be used.
 *
 * <p>For example, the following examples are valid:
 * <ul>
 *     <li>"time.android.com"</li>
 *     <li>"ntp://time.android.com"</li>
 *     <li>"ntp://time.android.com:123"</li>
 *     <li>"time.android.com|time.other"</li>
 *     <li>"ntp://time.android.com:123|ntp://time.other:123"</li>
 *     <li>"time.android.com|ntp://time.other:123"</li>
 * </ul>
 *
 * @hide
 */
@Readable
public static final String NTP_SERVER = "ntp_server";

Re-constification of libstd has commenced