pgsql: Add pg_table_size() and pg_indexes_size() to provide more

Log Message:
-----------
Add pg_table_size() and pg_indexes_size() to provide more user-friendly
wrappers around the pg_relation_size() function.

Bernd Helmle, reviewed by Greg Smith

Modified Files:
--------------
    pgsql/doc/src/sgml:
        func.sgml (r1.496 -> r1.497)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml?r1=1.496&r2=1.497)
    pgsql/src/backend/utils/adt:
        dbsize.c (r1.26 -> r1.27)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/dbsize.c?r1=1.26&r2=1.27)
    pgsql/src/include/catalog:
        catversion.h (r1.574 -> r1.575)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h?r1=1.574&r2=1.575)
        pg_proc.h (r1.562 -> r1.563)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h?r1=1.562&r2=1.563)
    pgsql/src/include/utils:
        builtins.h (r1.343 -> r1.344)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/builtins.h?r1=1.343&r2=1.344)