LazFileUtils: fix FileAgeUTF8 on Windows when FileName contains unicode
characters outside current codepage.


git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41287 4005530d-fff6-0310-9dd1-cebe43e6787f
LazFileUtils: inline FileAgeUTF8 to LazFileUtils.FileAgeUTF8


git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41288 4005530d-fff6-0310-9dd1-cebe43e6787f