typo on libpq.sgml

Hi, 

I noticed a typo in libpq.sgml. In the folowing partagrasoh, 'TCP_KEEPINTVL' 
should be 'TCP_KEEPCNT'. (In libpq's setKeepalivesCount(), '#ifdef TCP_KEEPCNT' is used.)

        
         keepalives_count
         
          
           Controls the number of TCP keepalives that can be lost before the
           client's connection to the server is considered dead.  A value of
           zero uses the system default. This parameter is ignored for
           connections made via a Unix-domain socket, or if keepalives are disabled.
           It is only supported on systems where the TCP_KEEPINTVL</>
           socket option is available; on other systems, it has no effect.
          
         
        

regards, 
-- 
  Shigehiro Honda