richmemo: fix for #23042, the patch by teejaydub - fixes hangs on win32 setrangeparams

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@2830 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/richmemo/win32/win32richmemoproc.pas

@@ -209,6 +209,7 @@ begin
   Result := false;
   if (RichEditWnd = 0) then Exit;
   
+  FillChar(textlen, sizeof(textlen), 0);
   textlen.flags := GTL_NUMCHARS or GTL_USECRLF or GTL_PRECISE;
   textlen.codepage := CP_UNICODE;
   len := SendMessage(RichEditWnd, EM_GETTEXTLENGTHEX, WPARAM(@textlen), 0);