ipset: install libraries to staging

Some packages may require libipset, for example keepalived.

Signed-off-by: Ilias Apalodimas <apalos@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/ipset/ipset.mk

@@ -13,5 +13,6 @@ IPSET_CONF_OPTS = --with-kmod=no
 IPSET_AUTORECONF = YES
 IPSET_LICENSE = GPLv2
 IPSET_LICENSE_FILES = COPYING
+IPSET_INSTALL_STAGING = YES
 
 $(eval $(autotools-package))