pgsql: Add $PostgreSQL$ marker to contrib makefiles.

Log Message:
-----------
Add $PostgreSQL$ marker to contrib makefiles.

Modified Files:
--------------
    pgsql/contrib/adminpack:
        Makefile (r1.3 -> r1.4)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/adminpack/Makefile.diff?r1=1.3&r2=1.4)
    pgsql/contrib/btree_gist:
        Makefile (r1.9 -> r1.10)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/btree_gist/Makefile.diff?r1=1.9&r2=1.10)
    pgsql/contrib/hstore:
        Makefile (r1.2 -> r1.3)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/hstore/Makefile.diff?r1=1.2&r2=1.3)
    pgsql/contrib/ltree:
        Makefile (r1.5 -> r1.6)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/ltree/Makefile.diff?r1=1.5&r2=1.6)
    pgsql/contrib/pg_standby:
        Makefile (r1.1 -> r1.2)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_standby/Makefile.diff?r1=1.1&r2=1.2)
    pgsql/contrib/pg_trgm:
        Makefile (r1.4 -> r1.5)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/pg_trgm/Makefile.diff?r1=1.4&r2=1.5)
    pgsql/contrib/sslinfo:
        Makefile (r1.7 -> r1.8)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/sslinfo/Makefile.diff?r1=1.7&r2=1.8)
    pgsql/contrib/tablefunc:
        Makefile (r1.6 -> r1.7)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tablefunc/Makefile.diff?r1=1.6&r2=1.7)
    pgsql/contrib/xml2:
        Makefile (r1.8 -> r1.9)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/xml2/Makefile.diff?r1=1.8&r2=1.9)