LazUtils: fix FileSetDateUtf8 for Windows, when file is in a folder with Unicode characters.
Fixes issue: 0023696. Patch based upon efforts of Takeda Matsuki.


git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@39893 4005530d-fff6-0310-9dd1-cebe43e6787f