Update schema for D7 upgrade

I compared schema in D6 and D7, and it looks like length of 'pass' field in {password_policy_history} table has changed from 32 to 128. However there is no hook_update_N() that does that change. Hence the problem. I also looked into 7.x-2.x branch, and this is not addressed there either.

I've put this code together to bridge the gap between 6.x-1.x and 7.x-1.x from looking at schema differences:

/**
 * Perform schema conversions for D6 -> D7 migration.
 */
function password_policy_update_7101() {
  db_change_field('password_policy', 'expiration', 'expiration', array(
    'description' => t("The passwords will expire after this number of days."),
    'type' => 'int',
    'default' => 0,
  ), array());
  db_change_field('password_policy_history', 'pass', 'pass', array(
    'description' => "User's password (hashed).",
    'type' => 'varchar',
    'length' => 128,
    'not null' => TRUE,
    'default' => '',
  ), array());
}

Please review and paste into password_policy.install.