Add .xspf association to win32 installer. Close #1964

(cherry picked from commit 6a85f39b)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

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

@@ -253,6 +253,7 @@ FunctionEnd
   !insertmacro ${_action} ".m3u"
   !insertmacro ${_action} ".pls"
   !insertmacro ${_action} ".vlc"
+  !insertmacro ${_action} ".xspf"
 !macroend
 
 ; One macro to rule them all