Clang: Change dot <-> arrow if all completions require it

Return the behavior that existed before completion fix-its
were introduced. Apply it only for the cases when all
items require the fix-it.

Fixes: QTCREATORBUG-21367
Change-Id: Idc358255135f72353f3fd3204b653fc2fc55e7a0
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/plugins/clangcodemodel/clangcompletionassistprocessor.h

@@ -85,6 +85,8 @@ private:
                                const QByteArray &customFileContent,
                                int functionNameStartPosition = -1);
 
+    CodeCompletions applyCompletionFixIt(const CodeCompletions &completions);
+
 private:
     struct Position { int line; int column; };
     Position extractLineColumn(int position);