* powerpc.cc (Stub_control::can_add_to_stub_group): Don't set
	owner when sections are not adjacent and exceed group size.
	(Target_powerpc::group_sections): Handle corner case.
	(Target_powerpc::Branch_info::make_stub): Handle case where
	stub table doesn't exist due to branches in non-exec sections.
	(Target_powerpc::Relocate::relocate): Likewise.