package/netsniff-ng: libnl is optional, not mandatory

libnl is optional, not mandatory, since version 0.6.2 and
https://github.com/netsniff-ng/netsniff-ng/commit/20a5e15443bfbbb7e6624a754832cdce19d462a0
https://github.com/netsniff-ng/netsniff-ng/commit/b073c8e5fd7f8c723680b659bd81afd231ef32f5

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/netsniff-ng/Config.in

@@ -3,7 +3,6 @@ config BR2_PACKAGE_NETSNIFF_NG
 	depends on BR2_TOOLCHAIN_HEADERS_AT_LEAST_3_0
 	depends on BR2_TOOLCHAIN_HAS_THREADS
 	depends on BR2_PACKAGE_LIBURCU_ARCH_SUPPORTS
-	select BR2_PACKAGE_LIBNL
 	select BR2_PACKAGE_LIBPCAP
 	select BR2_PACKAGE_LIBNETFILTER_CONNTRACK
 	select BR2_PACKAGE_LIBURCU

package/netsniff-ng/netsniff-ng.mk

@@ -13,7 +13,8 @@ NETSNIFF_NG_LICENSE_FILES = README COPYING
 NETSNIFF_NG_CONF_ENV = \
 	NACL_INC_DIR=/dev/null \
 	NACL_LIB_DIR=/dev/null
-NETSNIFF_NG_DEPENDENCIES = host-pkgconf libnl libpcap libnetfilter_conntrack liburcu
+NETSNIFF_NG_DEPENDENCIES = host-pkgconf libpcap libnetfilter_conntrack liburcu
+NETSNIFF_NG_CONF_OPTS = --prefix=$(TARGET_DIR)/usr
 
 ifeq ($(BR2_PACKAGE_NETSNIFF_NG_MAUSEZAHN),y)
 NETSNIFF_NG_DEPENDENCIES += libcli libnet
@@ -28,6 +29,12 @@ ifeq ($(BR2_PACKAGE_GEOIP),y)
 NETSNIFF_NG_DEPENDENCIES += geoip
 endif
 
+ifeq ($(BR2_PACKAGE_LIBNL),y)
+NETSNIFF_NG_DEPENDENCIES += libnl
+else
+NETSNIFF_NG_CONF_OPTS += --disable-libnl
+endif
+
 ifeq ($(BR2_PACKAGE_NCURSES),y)
 NETSNIFF_NG_DEPENDENCIES += ncurses
 endif
@@ -43,7 +50,7 @@ define NETSNIFF_NG_CONFIGURE_CMDS
 		$(TARGET_CONFIGURE_ARGS) \
 		$(TARGET_CONFIGURE_OPTS) \
 		./configure \
-		--prefix=$(TARGET_DIR)/usr \
+		$(NETSNIFF_NG_CONF_OPTS) \
 	)
 endef