* powerpc.cc (Powerpc_relobj::get_opd_ent): Make const.

	* powerpc.cc (Powerpc_relobj::get_opd_ent): Make const.
	(Powerpc_relocate_functions::Status): New typedef.
	(Target_powerpc::Scan::get_reference_flags): Handle more relocs.
	(Target_powerpc::Scan::local): Handle REL64.
	(Target_powerpc::Scan::global): Likewise, and dynamic relocs
	for REL32 and REL64.
	(Target_powerpc::symval_for_branch): New function, extracted from..
	(Target_powerpc::Relocate::relocate): ..here.  Correct plt call
	checks.  Report overflow errors.