[GOLD] PPC64_OPT_LOCALENTRY is incompatible with tail calls

[GOLD] PPC64_OPT_LOCALENTRY is incompatible with tail calls

Gold version of commit 3cd7c7d7ef.

	* powerpc.cc (Target_powerpc): Rename power10_stubs_ to
	power10_relocs_.
	(Target_powerpc::set_power10_relocs): New accessor.
	(Target_powerpc::set_power10_stubs): Delete.
	(Target_powerpc::power10_stubs): Adjust.
	(Target_powerpc::has_localentry0): New accessor.
	(ld_0_11): New constant.
	(glink_eh_frame_fde_64v1, glink_eh_frame_fde_64v2): Adjust.
	(glink_eh_frame_fde_64v2_localentry0): New.
	(Output_data_glink::pltresolve_size): Update.
	(Output_data_glink::add_eh_frame): Use localentry0 version eh_frame.
	(Output_data_glink::do_write): Move r2 save to start of ELFv2 stub
	and only emit for has_localentry0.  Don't use r2 in the stub.
	(Target_powerpc::Scan::local, global): Adjust for
	set_power10_relocs renaming.
	(Target_powerpc::scan_relocs): Warn and reset plt_localentry0_.