SideBySideDiffEditor: Avoid code repetition

Change-Id: Ie49834a4896dbf32a87329345e52dc99ca2f86bd
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/diffeditor/diffutils.h

@@ -4,6 +4,7 @@
 #pragma once
 
 #include "diffeditor_global.h"
+#include "diffenums.h"
 
 #include <utils/algorithm.h>
 
@@ -18,12 +19,6 @@ namespace Utils { class Diff; }
 
 namespace DiffEditor {
 
-enum DiffSide {
-    LeftSide,
-    RightSide,
-    SideCount // Use only in array declarations
-};
-
 class DIFFEDITOR_EXPORT DiffFileInfo {
 public:
     enum PatchBehaviour {