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.

When -reincarnate-reexec is given we run execv to restart FS.  If
argv[0] isn't a full pathname then execv is going to fail.  While not
common for a FS system started by init, this is a common occurrence
when FS is started from the shell.

Now if execv fails, we'll try execvp.  If that fails too then we'll
fall back on the normal reincarnation behavior.

Previously what would happen in that case is god would descend from
the heavens and become mortal.  Leaving heaven absent, all hope for
reincarnation was lost.

(That is, we'd simply return from reincarnate_protect and the
supervisor process would become the new instance of FS, so the trick
would only work once.)