Add a debug CLI command to seed random(3).

Add a debug CLI command to seed random(3).

This is a lot less useful than it could have been, as the Open Group
only mandates that:

	Like rand(), random() shall produce by default a sequence
	of numbers that can be duplicated by calling srandom() with
	1 as the seed.

But crucially leaves out *which* sequence of numbers.

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@3366 d4fa192b-c00b-0410-8231-f00ffab90ce4