* configure.ac: Add --with-lib-path option. Define LIB_PATH and

	* configure.ac: Add --with-lib-path option.  Define LIB_PATH and
	NATIVE_LINKER.
	* Makefile.am (AM_CPPFLAGS): Define TOOLLIBDIR.
	* options.cc (General_options::finalize): Use library search path
	from configure script if specified.  If not native and no sysroot,
	only search TOOLLIBDIR.
	* options.h (Search_directory::Search_directory): Change name to
	const std::string&.
	(General_options::add_to_library_path_with_sysroot): Change arg to
	const std::string&.
	* configure, Makefile.in, config.in: Rebuild.