skeleton: add /etc/nsswitch.conf

Toolchain Linaro 2012_09 and possibly other glibc based ones
rely on the existence of nsswitch.conf. If it's missing names
from /etc/hosts are not resolved and thus "localhost" is not
known.

Signed-off-by: Stephan Hoffmann <sho@relinux.de>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>