[Buildroot] get initial entropy from the host

[Enoch W.]

Hi, 

Thanks for making Linux so easy to build [that is, when it works ;-) ]

package/initscripts/init.d/S20urandom doesn't have readily available entropy on its first boot.
May I suggest initializing /dev/urandom from host generated random-seed. I do it now via my board post-build.sh as follows.
IMHO it should be done as standard.

umask 077
dd if=/dev/urandom of=${TARGET_DIR}/etc/random-seed count=1

Thanks, Enoch.