each version of Unordered_map.
	* layout.cc (Layout::Layout): Remove options parameter.  Add
	number_of_input_files parameter.  Don't initialize options_.
	Initialize number_of_input_files_ and resized_signatures_.  Move
	sections_are_attached_.
	(Layout::layout_group): Reserve space for group_signatures_.
	(Layout::find_or_add_kept_section): Change name parameter to be a
	reference.  Resize signatures_ map when it gets large enough.
	(Layout::layout_eh_frame): Use parameters->options() instead of
	this->options_.
	(Layout::make_output_section): Likewise.
	(Layout::attach_allocated_section_to_segment): Likewise.
	(Layout::finalize, Layout::create_executable_stack): Likewise.
	(Layout::set_segment_offsets, Layout::create_interp): Likewise.
	(Layout::finish_dynamic_section, Layout::write_binary): Likewise.
	* layout.h (class Layout): Update declarations.  Remove options_
	field.  Add number_of_input_files_ and resized_signatures_
	fields.  Move sections_are_attached_ field.
	* main.cc (main): Pass number of input files to Layout
	constructor.  Don't pass options.