Remove an duplicate definition of nhops_dump_sysctl()

One of the source files included both nhop.h and shared.h, leading to this
clashing.

Tested with: mips-gcc cross toolchain

sys/net/route/nhop.h

@@ -177,8 +177,6 @@ uint32_t nhop_get_idx(const struct nhop_object *nh);
 enum nhop_type nhop_get_type(const struct nhop_object *nh);
 int nhop_get_rtflags(const struct nhop_object *nh);
 
-int nhops_dump_sysctl(struct rib_head *rh, struct sysctl_req *w);
-
 #endif /* _KERNEL */
 
 /* Kernel <> userland structures */

sys/net/rtsock.c

@@ -78,6 +78,7 @@
 #include <netinet6/scope6_var.h>
 #endif
 #include <net/route/nhop.h>
+#include <net/route/shared.h>
 
 #ifdef COMPAT_FREEBSD32
 #include <sys/mount.h>