You need to qualify calls to FindFirst, FindNext, and FindClose to include the SysUtils unit. Example:

begin
    Result := SysUtils.FindFirst(Path, Attr, SearchRec);
    while Result = 0 do
    begin
      ProcessSearchRec(SearchRec);
      Result :=  SysUtils.FindNext(SearchRec);
    end;
     SysUtils.FindClose(SearchRec);
end;