We should not send UNLOAD_DLL_DEBUG_EVENT after sending EXIT_PROCESS_DEBUG_EVENT

This is worth 30 seconds in kernel32:process.
(in the function test_DebuggingFlag, the debug loop is exited after EXIT_PROCESS_DEBUG_EVENT.
However, after that reactos tries to send a UNLOAD_DLL_DEBUG_EVENT, and thus waits for another ContinueDebugEvent.