advpack: DelNode support the ADN_DEL_IF_EMPTY flag
Fixes a bug where rundll32.exe advpack.dll,DelNodeRunDLL32 "c:\test",1
is only supposed to delete "test" if the directory is empty.
Also causes the DelDirs Inf section to work correctly.
Notes:
- I changed the code so it ignores the result of
SetFileAttributesW
because the user might not have FILE_WRITE_ATTRIBUTES even if they have DELETE rights. This seems to match Windows (XP NTFS).