examples: nfct-daemon: Fix test building on musl libc
examples: nfct-daemon: Fix test building on musl libc

On musl libc, sys/select.h is where FD_* definitions are located.

Signed-off-by: Kylie McClain <24837c10191c459d7ff27b972503d6659bbadac0@exherbo.org>
Signed-off-by: Pablo Neira Ayuso <707d14912bb250caf67dfe0ea4035681fbfc4f56@netfilter.org>

greearb/libmnl-ct,greearb/libmnl-ct