Win32: do not delete preferences by default on install

(cherry picked from commit baa2d2c3b3f658e90d7ddf66e0e9c0eaa1a88446)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

extras/package/win32/vlc.win32.nsi.in

@@ -701,7 +701,7 @@ Section $Name_Section07 SEC07
   !insertmacro AddContextMenuExt "Directory"
 SectionEnd
 
-Section $Name_Section08 SEC08
+Section /o $Name_Section08 SEC08
   !insertmacro delprefs
 SectionEnd