maintained separately from the kernel.
You can obtain somewhat infrequent snapshots of klibc from
-ftp://ftp.kernel.org/pub/linux/libs/klibc/
+https://www.kernel.org/pub/linux/libs/klibc/
For active users, you are better off using the klibc git
repository, at http://git.kernel.org/?p=libs/klibc/klibc.git