fix spurious inferior interruption (attempts ...)

when queuing up commands, don't interrupt if we are already waiting
for interruption. that will be the case when other commands area already
queued.

src/plugins/debugger/gdb/gdbengine.cpp

@@ -703,10 +703,12 @@ void GdbEngine::postCommandHelper(const GdbCommand &cmd)
             flushCommand(cmd);
         } else {
             // Queue the commands that we cannot send at once.
-            showStatusMessage(tr("Stopping temporarily."), 1000);
             debugMessage(_("QUEUING COMMAND ") + cmd.command);
             m_commandsToRunOnTemporaryBreak.append(cmd);
-            interruptInferior(); // FIXME: race condition between gdb and kill()
+            if (state() != InferiorStopping) {
+                showStatusMessage(tr("Stopping temporarily."), 1000);
+                interruptInferior(); // FIXME: race condition between gdb and kill()
+            }
         }
     } else if (!cmd.command.isEmpty()) {
         flushCommand(cmd);