pgsql: Rename the uninstall scripts for contrib/lo and contrib/tsearch2

Log Message:
-----------
Rename the uninstall scripts for contrib/lo and contrib/tsearch2 to
match the convention that foo's uninstall script is uninstall_foo.sql.
Also, stop installing lo_test.sql, which really ought to be made into
a regression test anyway (though it's unclear how to avoid a dependency
on the current OID counter...)

Modified Files:
--------------
    pgsql/contrib/lo:
        Makefile (r1.14 -> r1.15)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/lo/Makefile.diff?r1=1.14&r2=1.15)
    pgsql/contrib/tsearch2:
        Makefile (r1.16 -> r1.17)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/tsearch2/Makefile.diff?r1=1.16&r2=1.17)

Added Files:
-----------
    pgsql/contrib/lo:
        uninstall_lo.sql (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/lo/uninstall_lo.sql?rev=1.1&content-type=text/x-cvsweb-markup)

Removed Files:
-------------
    pgsql/contrib/lo:
        lo_drop.sql
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/contrib/lo/lo_drop.sql)