(futimens): Robustify the previous patch, by checking

for known valid error numbers rather than observed invalid ones.

lib/utimens.c

@@ -81,10 +81,16 @@ futimens (int fd ATTRIBUTE_UNUSED,
 	return 0;
 
       /* On GNU/Linux without the futimes syscall and without /proc
-	 mounted, glibc futimes fails with errno == ENOENT or ENOSYS.
-	 Fall back on utimes in this case.  */
-      if (errno != ENOENT && errno != ENOSYS)
-	return -1;
+	 mounted, glibc futimes fails with errno == ENOENT.  Fall back
+	 on utimes if we get a weird error number like that.  */
+      switch (errno)
+	{
+	case EACCES:
+	case EIO:
+	case EPERM:
+	case EROFS:
+	  return -1;
+	}
     }
 # endif
   return utimes (file, t);