Linker used to skip RTLD_NEXT within local_group when
caller->next is nullptr (which represents load order
but not the order within local_group dependency tree)
Bug: http://b/21380474
Change-Id: I178fc4657b19bceb871635b177c1df67855b1708
(cherry picked from commit b96ac41b32e61799c48f3fd07831cc168b95068d)