[GOLD] Got_entry::write addends

[GOLD] Got_entry::write addends

This takes care of writing out GOT entries with addends.  The local
symbol case was already largely handled, except for passing the addend
to tls_offset_for_local which might need the addend in a
local_got_offset call.  That's needed also in tls_offset_for_global.

I'm assuming here that GOT entries for function symbols won't ever
have addends, and in particular that a GOT entry referencing PLT call
stub code won't want an offset into the code.

	PR 28192
	* output.cc (Output_data_got::Got_entry::write): Include addend
	in global symbol value.  Pass addend to tls_offset_for_*.
	* powerpc.cc (Target_powerpc::do_tls_offset_for_local): Handle addend.
	(Target_powerpc::do_tls_offset_for_global): Likewise.
	* s390.cc (Target_s390::do_tls_offset_for_local): Likewise.
	(Target_s390::do_tls_offset_for_global): Likewise.
	* target.h (Target::tls_offset_for_local): Add addend param.
	(Target::tls_offset_for_global): Likewise.
	(Target::do_tls_offset_for_local): Likewise.
	(Target::do_tls_offset_for_global): Likewise.