Changed the formerly pure virtual function:

namespace lldb_private {
    class Thread
    {
        virtual lldb::StopInfoSP
        GetPrivateStopReason() = 0;
    };
}

To not be virtual. The lldb_private::Thread now handles the correct caching and will call a new pure virtual function:

namespace lldb_private {
    class Thread
    {
        virtual bool
        CalculateStopInfo() = 0;
    }
}

This function must be overridden by thead lldb_private::Thread subclass and the only thing it needs to do is to set the Thread::StopInfo() with the current stop reason and return true, or return false if there is no stop reason. The  lldb_private::Thread class will take care of calling this function only when it is required. This allows lldb_private::Thread subclasses to be a bit simpler and not all need to duplicate the cache and invalidation settings.

Also renamed:

lldb::StopInfoSP
lldb_private::Thread::GetPrivateStopReason();

To:

lldb::StopInfoSP
lldb_private::Thread::GetPrivateStopInfo();

Also cleaned up a case where the ThreadPlanStepOverBreakpoint might not re-set its breakpoint if the thread disappears (which was happening due to a bug when using the OperatingSystem plug-ins with memory threads and real threads).

llvm-svn: 181501