win32: deactivate natpmp contrib

Change-Id: I843431c6062a66d01661c22cf87c5d18ab0bf810
Reviewed-by: Guillaume Roguez <guillaume.roguez@savoirfairelinux.com>

contrib/src/natpmp/rules.mak

@@ -2,11 +2,13 @@
 NATPMP_VERSION := 20150609
 NATPMP_URL := http://miniupnp.free.fr/files/download.php?file=libnatpmp-$(NATPMP_VERSION).tar.gz
 
+ifndef HAVE_WIN32
 ifndef HAVE_ANDROID
 ifndef HAVE_IOS
 PKGS += natpmp
 endif
 endif
+endif
 
 ifeq ($(call need_pkg,'libnatpmp'),)
 PKGS_FOUND += natpmp