elfcpp/:

elfcpp/:
	* elfcpp_file.h: Fix header guard.  Include <cstdio>.
	(class Elf_recognizer): New class, code from gold/object.cc.
	(Elf_file::find_section_by_type): New method.
gold/:
	* incremental.cc: Include <cstdarg> and "target-select.h".
	(vexplain_no_incremental): New function.
	(explain_no_incremental): New function.
	(Incremental_binary::error): New method.
	(Sized_incremental_binary::do_find_incremental_inputs_section): New
	method.
	(make_sized_incremental_binary): New function.
	(open_incremental_binary): New function.
	(can_incrementally_link_file): Add checks if output is ELF and has
	inputs section.
	* incremental.h: Include "elfcpp_file.h" and "output.h".
	(Incremental_binary): New class.
	(Sized_incremental_binary): New class.
	(open_incremental_binary): Declare.
	* object.cc (is_elf_object): Use
	elfcpp::Elf_recognizer::is_elf_file.
	(make_elf_object): Use elfcpp::Elf_recognizer::is_valid_header.
	* output.h (Output_file::filesize): New method.