Only include local addr as peer addr if provided

Only include local addr as peer addr if provided

we're using libnl-1.1 for a project. When trying to delete all
addresses of an interface by only setting interface index and
address family of an rtnl_addr and executing rtnl_addr_delete()
we received some error (I don't remember what it was).

The bug(?) is in build_addr_msg() in lib/route/addr.c:
IFA_ADDRESS is set to a_local when a_peer is not set,
without checking if a_local was set. We just added
   if (tmpl->ce_mask & ADDR_ATTR_LOCAL)
after the "else" (line 496 in the current git).