Doh! missed a spot.

 -Erik

libc/stdlib/atexit.c

@@ -168,7 +168,9 @@ void __exit_handler(int status)
 #ifdef L_exit
 extern void weak_function _stdio_term(void);
 void (*__exit_cleanup) (int) = 0;
+#ifdef __UCLIBC_HAS_THREADS__
 pthread_mutex_t mylock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
+#endif
 
 /*
  * Normal program termination