use freestanding headers

include/zinnia/stdlib.h

@@ -0,0 +1,8 @@
+#pragma once
+
+#include <stdint.h>
+
+int64_t atol(const char* str, int base);
+uint64_t atolu(const char* str, int base);
+char* lutoa(uint64_t value, char* str, int base);
+char* ltoa(int64_t value, char* str, int base);