include: fix missing struct nlmsghdr without definition

The definition of this structure belongs to the scope of
linux/netlink.h.

Based on patch from Jan Engelhardt.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/libnftables/set.h b/include/libnftables/set.h
index e377826..14a6327 100644
--- a/include/libnftables/set.h
+++ b/include/libnftables/set.h
@@ -30,6 +30,8 @@ const void *nft_set_attr_get(struct nft_set *s, uint16_t attr);
 const char *nft_set_attr_get_str(struct nft_set *s, uint16_t attr);
 uint32_t nft_set_attr_get_u32(struct nft_set *s, uint16_t attr);
 
+struct nlmsghdr;
+
 struct nlmsghdr *nft_set_nlmsg_build_hdr(char *buf, uint16_t cmd, uint16_t family, uint16_t type, uint32_t seq);
 void nft_set_nlmsg_build_payload(struct nlmsghdr *nlh, struct nft_set *s);
 int nft_set_nlmsg_parse(const struct nlmsghdr *nlh, struct nft_set *s);