make GetCodeName accessor more standard

Change-Id: Ieee004ef7f6c7db5503a8a0d1660785105ec0511
Reviewed-on: https://gerrit.libreoffice.org/59251
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

sc/inc/table.hxx

@@ -366,7 +366,7 @@ public:
     void        SetAnonymousDBData(std::unique_ptr<ScDBData> pDBData);
     ScDBData*   GetAnonymousDBData() { return pDBDataNoName.get();}
 
-    void        GetCodeName( OUString& rName ) const {  rName = aCodeName; }
+    const OUString& GetCodeName() const { return aCodeName; }
     void        SetCodeName( const OUString& rNewName ) { aCodeName = rNewName; }
 
     const OUString& GetUpperName() const;

sc/source/core/data/document.cxx

@@ -250,7 +250,7 @@ bool ScDocument::GetCodeName( SCTAB nTab, OUString& rName ) const
     if (ValidTab(nTab) && nTab < static_cast<SCTAB>(maTabs.size()))
         if (maTabs[nTab])
         {
-            maTabs[nTab]->GetCodeName( rName );
+            rName = maTabs[nTab]->GetCodeName();
             return true;
         }
     rName.clear();