fix memory leak around function descriptions

Found by Lsan.

Change-Id: Ia443ed6eb2a20854998a615f3c2bd9fdac156a8c

formula/source/ui/dlg/FormulaHelper.cxx

@@ -21,6 +21,8 @@
 #include <unotools/charclass.hxx>
 #include <unotools/syslocale.hxx>
 
+#include <boost/scoped_ptr.hpp>
+
 namespace formula
 {
 
@@ -91,7 +93,7 @@ bool FormulaHelper::GetNextFunc( const OUString&  rFormula,
             const sal_uInt32 nCategoryCount = m_pFunctionManager->getCount();
             for(sal_uInt32 j= 0; j < nCategoryCount && !*ppFDesc; ++j)
             {
-                const IFunctionCategory* pCategory = m_pFunctionManager->getCategory(j);
+                boost::scoped_ptr<const IFunctionCategory> pCategory(m_pFunctionManager->getCategory(j));
                 const sal_uInt32 nCount = pCategory->getCount();
                 for(sal_uInt32 i = 0 ; i < nCount; ++i)
                 {

include/formula/IFunctionDescription.hxx

@@ -60,7 +60,7 @@ namespace formula
         ~IFunctionManager() {}
     };
 
-    class SAL_NO_VTABLE IFunctionCategory
+    class IFunctionCategory
     {
     public:
         IFunctionCategory(){}
@@ -70,8 +70,7 @@ namespace formula
         virtual sal_uInt32                  getNumber() const = 0;
         virtual OUString             getName() const = 0;
 
-    protected:
-        ~IFunctionCategory() {}
+        virtual ~IFunctionCategory() {}
     };
 
     class SAL_NO_VTABLE IFunctionDescription