add directory kernel

kernel/0.1x/linux-0.12/lib/_exit.c

@@ -0,0 +1,13 @@
+/*
+ *  linux/lib/_exit.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+#define __LIBRARY__
+#include <unistd.h>
+
+volatile void _exit(int exit_code)
+{
+	__asm__("int $0x80"::"a" (__NR_exit),"b" (exit_code));
+}