[GOLD] Remove addend from Local_got_entry_key

[GOLD] Remove addend from Local_got_entry_key

This patch removes the addend from Local_got_entry_key, which is
unnecessary now that Got_offset_list has an addend.  Note that it
might be advantageous to keep the addend in Local_got_entry_key when
linking objects containing a large number of section_sym+addend@got
relocations.  I opted to save some memory by removing the field but
left the class there in case we might need to restore {sym,addend}
lookup.  That's also why this change is split out from the
Got_offset_list change.

	PR 28192
	* object.h (Local_got_entry_key): Delete addend_ field.
	Adjust constructor and methods to suit.
	* object.cc (Sized_relobj::do_for_all_local_got_entries):
	Update key.