Clang: Don't send multiple completions for the same position

If we send already a completion we should test if there is already one
sent for the same position.

Change-Id: Ie88f89bff0e1da1c5e747827a45154c7ccaecabc
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@theqtcompany.com>
Reviewed-by: Marco Bubke <marco.bubke@theqtcompany.com>

src/plugins/clangcodemodel/clangbackendipcintegration.h

@@ -76,6 +76,8 @@ public:
     void deleteAndClearWaitingAssistProcessors();
     void deleteProcessorsOfEditorWidget(TextEditor::TextEditorWidget *textEditorWidget);
 
+    bool isExpectingCodeCompletedMessage() const;
+
 private:
     void alive() override;
     void echo(const ClangBackEnd::EchoMessage &message) override;
@@ -152,6 +154,8 @@ public:
     void registerFallbackProjectPart();
     void updateTranslationUnitVisiblity();
 
+    bool isNotWaitingForCompletion() const;
+
 public: // for tests
     IpcSenderInterface *setIpcSender(IpcSenderInterface *ipcSender);
     void killBackendProcess();