pg_dump segfaults with publication

Hi,

pg_dump segfaults if there are more than one DO_PUBLICATION_REL objects to
dump.

create table foo (a int);
create publication foo_pub;
alter publication foo_pub add table foo;

$ pg_dump
<OK>

create table bar (a int);
alter publication foo_pub add table bar;

$ pg_dump -s
Segmentation fault (core dumped)

The reason is DumpableObject.name is not set being set in
getPublicationTables(). Attached patch fixes that.

Thanks,
Amit