[lldb] Convert MainLoopWindows.cpp to new Status API (NFC)

(cherry picked from commit f00c946)

Author: adrian-prantl

lldb/source/Host/windows/MainLoopWindows.cpp

@@ -121,7 +121,7 @@ Status MainLoopWindows::Run() {
 
     llvm::Expected<size_t> signaled_event = Poll();
     if (!signaled_event)
-      return Status(signaled_event.takeError());
+      return Status::FromError(signaled_event.takeError());
 
     if (*signaled_event < m_read_fds.size()) {
       auto &KV = *std::next(m_read_fds.begin(), *signaled_event);