pgsql: Change -> and <- to use proper ampersand markups.

Log Message:
-----------
Change -> and <- to use proper ampersand markups.

HEAD and 8.0.X.

Tags:
----
REL8_0_STABLE

Modified Files:
--------------
    pgsql/doc/src/sgml:
        cvs.sgml (r1.30 -> r1.30.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/cvs.sgml.diff?r1=1.30&r2=1.30.4.1)
        indexcost.sgml (r2.18 -> r2.18.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/indexcost.sgml.diff?r1=2.18&r2=2.18.4.1)
        plhandler.sgml (r1.4 -> r1.4.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/plhandler.sgml.diff?r1=1.4&r2=1.4.4.1)
        release.sgml (r1.321 -> r1.321.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/release.sgml.diff?r1=1.321&r2=1.321.4.1)
        rules.sgml (r1.37 -> r1.37.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/rules.sgml.diff?r1=1.37&r2=1.37.4.1)
        spi.sgml (r1.37 -> r1.37.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/spi.sgml.diff?r1=1.37&r2=1.37.4.1)
        trigger.sgml (r1.39 -> r1.39.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/trigger.sgml.diff?r1=1.39&r2=1.39.4.1)
        xfunc.sgml (r1.96 -> r1.96.4.1)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/xfunc.sgml.diff?r1=1.96&r2=1.96.4.1)