Use unsigned values in m_a(Converted)BoundValues

Values that come from the database are always signed
(we inherit that from sdbc that inherits that from jdbc
 that inherits that from Java's type system that does not have unsigned values)
So when using unsigned values, they always operator==-compare false!

Change-Id: I604b04afa23ede835c1f3db1f8c1bdeafbfba7ea

forms/source/component/ListBox.cxx

@@ -912,7 +912,7 @@ namespace frm
                             aBoundValue.fill( *aBoundColumn + 1, m_nBoundColumnType, xCursorRow );
                         else
                             // -1 because getRow() is 1-indexed, but ListBox positions are 0-indexed
-                            aBoundValue = static_cast<sal_uInt16>(xListCursor->getRow()-1);
+                            aBoundValue = static_cast<sal_Int16>(xListCursor->getRow()-1);
                         aValueList.push_back( aBoundValue );
 
                         if ( bUseNULL && ( m_nNULLPos == -1 ) && aStr.isEmpty() )