libbpf: Move __dump_nlmsg_t from API to implementation

This typedef is used only by implementation in netlink.c. Nothing uses
it in public API. Move it to netlink.c.

Signed-off-by: Andrey Ignatov <[e-mail]>
Acked-by: Alexei Starovoitov <[e-mail]>
Signed-off-by: Daniel Borkmann <[e-mail]>

tools/lib/bpf/libbpf.h

···
 			       void **buf, size_t *buf_len,
 			       bpf_perf_event_print_t fn, void *priv);
 
-struct nlmsghdr;
 struct nlattr;
 typedef int (*dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);
-typedef int (*__dump_nlmsg_t)(struct nlmsghdr *nlmsg, dump_nlmsg_t,
-			      void *cookie);
 int bpf_netlink_open(unsigned int *nl_pid);
 int nl_get_link(int sock, unsigned int nl_pid, dump_nlmsg_t dump_link_nlmsg,
 		void *cookie);

tools/lib/bpf/netlink.c

···
 #define SOL_NETLINK 270
 #endif
 
+typedef int (*__dump_nlmsg_t)(struct nlmsghdr *nlmsg, dump_nlmsg_t,
+			      void *cookie);
+
 int bpf_netlink_open(__u32 *nl_pid)
 {
 	struct sockaddr_nl sa;