DiffEditor: Fix jumping to context line immediately on git show

Fixes: QTCREATORBUG-29081
Change-Id: I7a4658209f95e98cb485e725dee07074dae5c163
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/diffeditor/diffeditor.h

@@ -53,6 +53,7 @@ private:
     void ignoreWhitespaceHasChanged();
     void prepareForReload();
     void reloadHasFinished(bool success);
+    void currentIndexChanged(int index);
     void setCurrentDiffFileIndex(int index);
     void documentStateChanged();