Possible revert needed to get Solaris tests passing

Talk to Matthew before merging this.

https://dev.cfengine.com/issues/6476

<pre>
Revert "Small cleanups of the PRNG seeding code."

This reverts commit 9e89ab0a22ff8d2b6187f04863eef64df52a6cfd.

The reason is that in a chroot testing environment, there isn't enough
entropy available to satisfy OpenSSL, so it will bail out. Reverting
is not the correct fix for the problem, but right now we need tests to
pass, so postponing this for later.

Conflicts:

	libpromises/crypto.c
</pre>
A sufficient fix would be to suppress this UnexpectedError(); make it a Log(SCARY, ...) instead, rather than reverting the whole change.