iw: fix static linking

Libnl needs explicit -lpthread / -lm when statically linking.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/iw/iw.mk

@@ -13,6 +13,12 @@ IW_MAKE_ENV = PKG_CONFIG_PATH="$(STAGING_DIR)/usr/lib/pkgconfig" \
 	PKG_CONFIG="$(HOST_DIR)/usr/bin/pkg-config" \
 	GIT_DIR=$(IW_DIR)
 
+ifeq ($(BR2_PREFER_STATIC_LIB),y)
+# libnl needs pthread/m, so we need to explicitly with them when static
+# these need to added AFTER libnl, so we have to override LIBS completely
+IW_MAKE_OPT = LIBS='-lnl-genl-3 -lnl-3 -lpthread -lm'
+endif
+
 define IW_CONFIGURE_CMDS
 	echo "CC = $(TARGET_CC)" >$(IW_CONFIG)
 	echo "CFLAGS = $(TARGET_CFLAGS)" >>$(IW_CONFIG)
@@ -20,7 +26,7 @@ define IW_CONFIGURE_CMDS
 endef
 
 define IW_BUILD_CMDS
-	$(IW_MAKE_ENV) $(MAKE) -C $(@D)
+	$(IW_MAKE_ENV) $(MAKE) $(IW_MAKE_OPT) -C $(@D)
 endef
 
 define IW_INSTALL_TARGET_CMDS