FS-6596 --resolve

test suite is now mostly OK with valgrind.

mod_rayo: rework component inheritance- component now inherits parent call/mixer mutex and parent reference counting moved to base class

This allows new settings, e.g. new mirrors, to propagate into the
chroot images.

There's really nothing to do but retry.

Sometimes while the debian repositories are updating there are
sporadic signature failures.  It's annoying to have these break the
build, and the only thing to do is to retry, so we'll retry here
automatically.  We were already retrying on the update operation that
can fail in a similar manner.