build system refresh

rlibc/include/unistd.h

@@ -0,0 +1,15 @@
+#ifndef RLIBC_UNISTD_H
+#define RLIBC_UNISTD_H
+
+#include <syscall.h>
+#include <sys/types.h>
+
+#define STDIN_FILENO  0
+#define STDOUT_FILENO 1
+#define STDERR_FILENO 2
+
+#define SEEK_SET 0
+#define SEEK_CUR 1
+#define SEEK_END 2
+
+#endif