buildroot

package: add libnss

NSS is the Network Security Services library developed as part of
the Mozilla project. It provides similar functions to OpenSSL but
allows MPL, GPL and LGPL licensing.

[Peter: fix target install]
Signed-off-by: Will Newton <will.newton@imgtec.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>