glibc security update

2.17-157.4 - Avoid large allocas in the dynamic linker 1452720 2.17-157.2 - Fix use of uninitialized data in getaddrinfo with nscd 1436312 2.17-157.1 - Do not set initgroups in default nsswitch.conf 1388638 - nssdb: Request larger buffers for long group entries 1388637 - nssdb: Fix getent crash...