Overhaul the varnishtest program to fix a race condition which might

Overhaul the varnishtest program to fix a race condition which might
(or might not) be the root cause of #346:

The delay function would access the toplevel log element from client/server
contexts with no logging.

Fix by passing the log element to the subcommands.

This race would only affect testcases using delay or sema inside client
or server threads.

Revert test a00008.vtc to use only one sema, using two just moved the
race condition.

This also has the side effect of moving "sema" related messages to
the tread that carries out the "sema" operation.

Various other cleanups now that I had my fingers in the code anyway:
memory leaks plugged, stylistic nits etc.

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@3272 d4fa192b-c00b-0410-8231-f00ffab90ce4