Fixed index error that was failing the script to run.

git-svn-id: http://svn.igniterealtime.org/svn/repos/wildfire/trunk/src/plugins/gateway@4689 b35dd754-fafc-0310-a699-88a17e54d16e

src/database/gateway_mysql.sql

@@ -7,7 +7,7 @@ CREATE TABLE gatewayRegistration (
    registrationDate  BIGINT         NOT NULL,
    lastLogin         BIGINT,
    PRIMARY KEY (registrationID),
-   INDEX gatewayReg_jid_idx(jid),
+   INDEX gatewayReg_jid_idx(jid(500)),
    INDEX gatewayReg_type_idx(transportType)
 );