skins2: replace unlink with vlc_unlink
skins2: replace unlink with vlc_unlink

(cherry picked from commit 5e3c93f14aa5084101b1a0adf527016b3a86904c)
Signed-off-by: Erwan Tulou <e27b355b6a481153648f03262de342e9eb9e2807@videolan.org>

jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2,jomanmuk/vlc-2.2