net-snmp: fix libnl dependency

When libnl-core is enabled, but libnl isn't, build fails because of a
missing dependency on libnl-3.so.200. Depending on libnl-core seems to
work for both cases.

Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>

net/net-snmp/Makefile

@@ -38,7 +38,7 @@ define Package/libnetsnmp
 $(call Package/net-snmp/Default)
   SECTION:=libs
   CATEGORY:=Libraries
-  DEPENDS:=+PACKAGE_libnl:libnl
+  DEPENDS:=+PACKAGE_libnl-core:libnl-core
   TITLE:=Open source SNMP implementation (libraries)
 endef