pgsql: Make libpq default to localhost connections on machines without

Log Message:
-----------
Make libpq default to localhost connections on machines without Unix-domain
sockets, rather than failing as it formerly did.  Revert the
thereby-obsoleted patch to make psql supply the localhost default.

Modified Files:
--------------
    pgsql/doc/src/sgml:
        libpq.sgml (r1.173 -> r1.174)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/libpq.sgml.diff?r1=1.173&r2=1.174)
    pgsql/doc/src/sgml/ref:
        psql-ref.sgml (r1.125 -> r1.126)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/psql-ref.sgml.diff?r1=1.125&r2=1.126)
    pgsql/src/bin/psql:
        startup.c (r1.106 -> r1.107)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/startup.c.diff?r1=1.106&r2=1.107)
    pgsql/src/interfaces/libpq:
        fe-connect.c (r1.292 -> r1.293)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/libpq/fe-connect.c.diff?r1=1.292&r2=1.293)