rootfs/etc: add krb5.conf

Signed-off-by: Adam Wujek <adam.wujek@cern.ch>

userspace/rootfs_override/etc/krb5.conf

+[libdefaults]
+        default_realm = CERN.CH
+        kdc_timesync = 1
+        ccache_type = 4
+        forwardable = true
+        proxiable = true