libpq: Add missing gettext markers

Follow-up to 87d2801: That commit restored some lost error
messages, but they ended up in a place where xgettext wouldn't find
them.  Rather than elevating ENCRYPTION_NEGOTIATION_FAILED() to a
gettext trigger, it's easiest for now to put in some explicit
libpq_gettext() calls in the couple of call sites.

Author: petere

src/interfaces/libpq/fe-connect.c

@@ -3519,7 +3519,7 @@ PQconnectPoll(PGconn *conn)
 						 * continue without SSL, we can proceed using this
 						 * connection.  Otherwise return with an error.
 						 */
-						ENCRYPTION_NEGOTIATION_FAILED("server does not support SSL, but SSL was required");
+						ENCRYPTION_NEGOTIATION_FAILED(libpq_gettext("server does not support SSL, but SSL was required"));
 					}
 					else if (SSLok == 'E')
 					{
@@ -3640,7 +3640,7 @@ PQconnectPoll(PGconn *conn)
 						 * continue without GSS, we can proceed using this
 						 * connection.  Otherwise return with an error.
 						 */
-						ENCRYPTION_NEGOTIATION_FAILED("server doesn't support GSSAPI encryption, but it was required");
+						ENCRYPTION_NEGOTIATION_FAILED(libpq_gettext("server doesn't support GSSAPI encryption, but it was required"));
 					}
 					else if (gss_ok != 'G')
 					{