make sure we pull in features.h

libc/stdio/_stdio.h

@@ -17,6 +17,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <features.h>
 
 #ifdef __UCLIBC_HAS_WCHAR__
 #include <wchar.h>