Updated postgresql9.3/4/6 packages fix security vulnerabilities

libpq, and by extension any connection driver that utilizes libpq, ignores empty passwords and does not transmit them to the server. When using libpq or a libpq-based connection driver to perform password-based authentication methods, it would appear that setting an empty password would be the equivalent of disabling password login. However, using a non-libpq based connection driver could allow a client with an empty password to log in (CVE-2017-7546). A user had access to see the options in pg_user_mappings even if the user did not have the USAGE permission on the associated foreign server. This meant that a user could see details such as a password that might have been set by the server administrator rather than the user (CVE-2017-7547). The lo_put() function should require the same permissions as lowrite(), but there was a missing permission check which would allow any user to change the data in a large object (CVE-2017-7548). Note: the CVE-2017-7547 issue requires manual intervention to fix on affected systems. See the references for details.