[Windows] Fix a bug that causes lldb to freeze

Summary:
If the process exits before any initial stop then notify the debugger 
of the error otherwise WaitForDebuggerConnection() will be blocked.
An example of this issue is when a process fails to load a dependent DLL.

In addition to the fix, remove a duplicate call to FreeProcessHandles() in 
DebuggerThread::HandleExitProcessEvent() and use decimal format 
for all thread IDs.

Reviewers: rnk, zturner, aleksandr.urakov

Reviewed By: zturner

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D53090

llvm-svn: 344168