Add atexit() and EOF to the kernel.

kernel/kernel.c

@@ -134,6 +134,12 @@ void exit(int status)
     while(1);
 }
 
+int atexit(void (*function)(void))
+{
+    /* FIXME: register function */
+    return 0;
+}
+
 /* string.h functions */
 void *memset(void *s, int c, size_t n)
 {

kernel/kernel.h

@@ -20,6 +20,7 @@
 
 /* Various defines */
 #define NULL ((void *)0)
+#define EOF (-1)
 #define BUFSIZ 4096
 #define RAND_MAX ((unsigned int)0x8000000)
 #define INT_MAX ((int)0x7fffffff)
@@ -77,6 +78,7 @@ int rand(void);
 int abs(int j);
 void exit(int status);
 void srand(unsigned int s);
+int atexit(void (*function)(void));
 FILE *stdin, *stdout, *stderr;
 
 /* string.h functions */