fpspreadsheet: Fix memory leak occuring when the parser of a previously allocated formula record is changed.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@6521 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/fpspreadsheet/source/common/fpsclasses.pas

@@ -1490,6 +1490,7 @@ begin
   if Result = nil then
     Result := PsFormula(Add(ARow, ACol));
   Result^.Text := AFormula;           // unparsed formula
+  FreeAndNil(Result^.Parser);         // Destroy previously existing parser
   Result^.Parser := AParsedFormula;   // if nil, will be parsed on next calculation
   Result^.CalcState := csNotCalculated;
 end;