NTFS mount points are not treated as symlinks, because they might
not have a link target.
This is the case when a volume is mounted as a single mount point
without a drive letter.
This patch fixes building Qt in an NTFS mount point.
Task-number: QTBUG-20431
Change-Id: Ie2e15212e1a7ca7fa0067b7ca8857e243e42c21a
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@nokia.com>