* system.h (string, algorithm): Include only conditionally.
	(new): Include always under C++.
	* bb-reorder.c (toplevel): Define INCLUDE_ALGORITHM.
	* final.c (toplevel): Ditto.
	* ipa-chkp.c (toplevel): Define INCLUDE_STRING.
	* genconditions.c (write_header): Make gencondmd.c define
	INCLUDE_STRING.
	* mem-stats.h (mem_usage::print_dash_line): Don't use std::string.

	* config/aarch64/aarch64.c (toplevel): Define INCLUDE_STRING.
	* common/config/aarch64/aarch64-common.c (toplevel): Ditto.

From-SVN: r232736