pgsql: Cause ALTER INDEX OWNER to generate a warning and do nothing,

Log Message:
-----------
Cause ALTER INDEX OWNER to generate a warning and do nothing, rather than
erroring out as it has done for the last couple weeks. Document that this
form is now ignored because indexes can't usefully have different owners
from their parent tables. Fix pg_dump to not generate ALTER OWNER commands
for indexes.

Modified Files:
--------------
pgsql/doc/src/sgml/ref:
alter_index.sgml (r1.5 -> r1.6)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_index.sgml.diff?r1=1.5&r2=1.6)
pgsql/src/backend/commands:
tablecmds.c (r1.167 -> r1.168)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/tablecmds.c.diff?r1=1.167&r2=1.168)
pgsql/src/bin/pg_dump:
pg_backup_archiver.c (r1.112 -> r1.113)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/pg_backup_archiver.c.diff?r1=1.112&r2=1.113)