pgsql: binary migration: pg_migrator Add comments about places where

Log Message:
-----------
binary migration:  pg_migrator

Add comments about places where system oids have to be preserved for
binary migration.

Modified Files:
--------------
    pgsql/src/backend/catalog:
        pg_enum.c (r1.9 -> r1.10)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/pg_enum.c?r1=1.9&r2=1.10)
    pgsql/src/backend/commands:
        typecmds.c (r1.139 -> r1.140)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/typecmds.c?r1=1.139&r2=1.140)
    pgsql/src/backend/utils/adt:
        arrayfuncs.c (r1.161 -> r1.162)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/arrayfuncs.c?r1=1.161&r2=1.162)
        enum.c (r1.7 -> r1.8)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/enum.c?r1=1.7&r2=1.8)
        rowtypes.c (r1.25 -> r1.26)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/rowtypes.c?r1=1.25&r2=1.26)