Be consistent: change `#ifndef _LIBC' to `#if !_LIBC'.

diff --git a/lib/error.c b/lib/error.c
index 56659d2..18c779e 100644 (file)
--- a/lib/error.c
+++ b/lib/error.c
@@ -55,7 +55,7 @@ void exit ();
 
 #include "error.h"
 
-#ifndef _LIBC
+#if !_LIBC
 # include "unlocked-io.h"
 #endif