Method set_size

lesson7-Detection/src/utils/tinystr.h:207–207

	void init(size_type sz) { init(sz, sz); }
	void set_size(size_type sz) { rep_->str[ rep_->size = sz ] = '\0'; }
	char* start() const { return rep_->str; }
	char* finish() const { return rep_->str + rep_->size; }