pgsql: Implement the <> operator for the tid type.

Log Message:
-----------
Implement the <> operator for the tid type. Original patch from Mark
Kirkwood, minor improvements by Neil Conway. The regression tests have
been updated and the catversion has been bumped.

Modified Files:
--------------
    pgsql/src/backend/utils/adt:
        tid.c (r1.49 -> r1.50)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/tid.c.diff?r1=1.49&r2=1.50)
    pgsql/src/include/catalog:
        catversion.h (r1.315 -> r1.316)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h.diff?r1=1.315&r2=1.316)
        pg_operator.h (r1.139 -> r1.140)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_operator.h.diff?r1=1.139&r2=1.140)
        pg_proc.h (r1.397 -> r1.398)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h.diff?r1=1.397&r2=1.398)
    pgsql/src/include/utils:
        builtins.h (r1.273 -> r1.274)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/builtins.h.diff?r1=1.273&r2=1.274)
    pgsql/src/test/regress/expected:
        transactions.out (r1.12 -> r1.13)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/transactions.out.diff?r1=1.12&r2=1.13)
    pgsql/src/test/regress/sql:
        transactions.sql (r1.12 -> r1.13)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/transactions.sql.diff?r1=1.12&r2=1.13)