[WIP] Patch : Change pg_ident.conf parsing to be the same as pg_hba.conf

<div class="WordSection1"><p><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">Attached is a Patch to
changethe parsing of pg_ident.conf to make it similar to pg_hba.conf. <br />This is based on Todo Item: <br /><a
href="http://archives.postgresql.org/pgsql-hackers/2011-06/msg02204.php">http://archives.postgresql.org/pgsql-hackers/2011-06/msg02204.php</a>
</span><p><spanstyle="font-size:10.0pt;font-family:"Arial","sans-serif"">Purpose - This will allow to catch syntax
errorsin pg_ident at the startup or reload time.<br />  <br />  <br />Changes are described as follows: <br />a.    
 Makethe load_ident() functionality same as load_hba, such that it cleans the previous context, after successful
parsing.<br />b.      Change the load_ident(), so that parsing can be done during load time and the parsed lines are
saved.<br />c.      Change the functionality of parse_ident_usermap() so that parsing is not done during
authentication.<br />d.      If load_ident() fails for parsing, it returns false and error is issued. <br
/>        Thispoint I am not sure, as for pg_hba failure it issues FATAL at startup. Currently I have kept error
handlingfor load of pg_ident same as pg_hba  <br />  <br />I have done the basic testing and test is still in progress.
<br/>  <br />Suggestions? <br />  <br />  <br />With Regards, <br />Amit Kapila. </span><p class="MsoNormal"> </div>