glibc: add security patches

Fix for 2.21 and 2.22:
CVE-2015-7547 - glibc getaddrinfo stack-based buffer overflow.

For 2.21:
CVE-2014-8121 - Unexpected closing of nss_files databases after lookups
causes denial of service.
CVE-2015-1781 - buffer overflow in gethostbyname_r() and related
functions with misaligned buffer.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>