* merge.h (Output_merge_string::Merged_string): Remove object, shndx,

	* merge.h (Output_merge_string::Merged_string): Remove object, shndx,
	string, and length fields.
	(Output_merge_string::Merged_strings_list): New type.
	(Output_merge_string::Merged_strings_lists): New typedef.
	(Output_merge_string): Replace merged_strings_ with
	merged_strings_lists_.
	* merge.cc (Output_merge_string::do_add_input_section): Allocate new
	Merged_strings_list per input object and section.  Don't store pointer
	to the string.  Don't store length with each merged string entry.
	(Output_merge_string::finalize_merged_data): Loop over list of merged
	strings lists.  Recompute length of each merged string.