Implement a framework for live debugging on Windows.

When processes are launched for debugging on Windows now, LLDB
will detect changes such as DLL loads and unloads, breakpoints,
thread creation and deletion, etc.

These notifications are not yet propagated to LLDB in a way that
LLDB understands what is happening with the process.  This only
picks up the notifications from the OS in a way that they can be
sent to LLDB with subsequent patches.

Reviewed by: Scott Graham

Differential Revision: http://reviews.llvm.org/D6037