[PATCH] urngd: Add support for read()ing entropy

[Nathaniel Filardo]

Someone should update https://openwrt.org/submitting-patches then, so
that the very first thing of "Patch Checklist" isn't "Single commit (
multiple commits must first be squashed, as described here )".  I of
course wrote it as multiple commits but was trying to follow
instructions. :(

Un-squashed version momentarily.

Cheers,
--nwf;