Reorder bosserver startup prior to pthreads

The rx calls will take locks when built in pthreaded mode, and must go
after rx_Init().  Some other setup would benefit from using time-domain
locking and should run before we go multithreaded.

In particular, initialize bozo_confdir while single-threaded, as it is
otherwise protected by the afsconf internal locking.  While here, pass
NULL to afsconf_SetCellInfo -- bozo_confdir would always be NULL there,
anyway.

Also move up ReadBozoFile so that it can benefit from time-domain
locking as well.  All that it needs is the bnode types to have been
registered and the bnode lock to have been initialized, and for any
daemonization to have already occurred.

Change-Id: Ib0cae83f3a4423330ae6f23d3a4112499d695618
Convert bosserver to pthreads

Well, mostly.  We're cheating because there isn't a libtoolized
procmgmt library yet, but it should be safe for now.

Don't bother retaining a LWP version; this stuff is not super
complicated and is subject to only light concurrency.

Add a global bnode mutex to protect the global state -- the various
bnode queues (though not the bnodes themselves), some compound time
structures that should get a consistent snapshot, and global flags.
Add a condition variable to each bnode for signalling.

The bnode reference counting scheme is not touched; it's current
state is fairly bogus and probably broken even with LWP semantics.

No locking is done on the contents of an individual bnode; simultaneous
callers could introduce inconsistent state (but this was already the
case).

Do not use the softsig implementation, which is known to be buggy
with pthreads.  Instead, use a self-pipe to the bproc thread, whose
sole purpose is to wait for signals and timeouts.

Move creation of the bproc thread to nearly as late as possible
(with the creation of the BozoDaemon thread), to take advantage
of time-domain locking for initialization which is done while
single-threaded.  This allows several globals to be unlocked,
as they are read-only while threaded.

Change-Id: I2865e1fb011d611dd664261ae7a8f21f7ce8d7b0