Change the Thread constructor over to take a Process& rather than a ProcessSP....

Change the Thread constructor over to take a Process& rather than a ProcessSP.  We can't create Threads with a NULL ProcessSP, so it makes no sense to use the SP.
Then make the Thread a Broadcaster, and get it to broadcast when the selected frame is changed (but only from the Command Line) and when Thread::ReturnFromFrame 
changes the stack.
Made the Driver use this notification to print the new thread status rather than doing it in the command.
Fixed a few places where people were setting their broadcaster class by hand rather than using the static broadcaster class call.

<rdar://problem/12383087>

llvm-svn: 165640