Add helper functions for thread testing.

kern/include/lib.h

@@ -194,5 +194,7 @@ void kprintf_bootstrap(void);
 #define DIVROUNDUP(a,b) (((a)+(b)-1)/(b))
 #define ROUNDUP(a,b)    (DIVROUNDUP(a,b)*b)
 
+void random_yielder(uint32_t);
+void random_spinner(uint32_t);
 
 #endif /* _LIB_H_ */

kern/include/overwrite.h

@@ -40,6 +40,6 @@
  * testing.
  */
 
-#define KERNEL_PROMPT    "OS/161 kernel [? for menu]: "
+#define KERNEL_PROMPT "OS/161 kernel [? for menu]: "
 
 #endif /* _OVERWRITE_H_ */