writerfilter: use std::unique_ptr<> in FontTable

Change-Id: I8dce4e71c53526605d83710012133784a5cbd7ba

writerfilter/source/dmapper/FontTable.cxx

@@ -49,7 +49,6 @@ FontTable::FontTable()
 
 FontTable::~FontTable()
 {
-    delete m_pImpl;
 }
 
 void FontTable::lcl_attribute(Id Name, Value & val)

writerfilter/source/dmapper/FontTable.hxx

@@ -56,7 +56,7 @@ struct FontEntry
 class FontTable : public LoggedProperties, public LoggedTable
     /*,public BinaryObj*/, public LoggedStream
 {
-    FontTable_Impl   *m_pImpl;
+    std::unique_ptr<FontTable_Impl> m_pImpl;
 
  public:
     FontTable();