[lldb] Always move the cursor back after printing progress

This got lost while iterating on the patch. We need to always move the
cursor to the front of the line so that if something else
(asynchronously) prints to the debugger's output it overwrites the
progress message.

lldb/source/Core/Debugger.cpp

@@ -1813,7 +1813,7 @@ void Debugger::HandleProgressEvent(const lldb::EventSP &event_sp) {
         "%s", ansi::FormatAnsiTerminalCodes(ansi_suffix, use_color).c_str());
 
   // Clear until the end of the line.
-  output.Printf("\x1B[K");
+  output.Printf("\x1B[K\r");
 
   // Flush the output.
   output.Flush();