route: add struct in6_rtmsg definition

adapts to third-party code compilation. in the process of porting ConnMan,
we encounter some situations where the structure is not defined, or the
returned data types do not match the expectations. Refer to the common
implementation of other systems and add relevant definitions.

Signed-off-by: zhanghongyu <[email protected]>

Author: zhhyu7

include/net/route.h

@@ -28,6 +28,7 @@
 #include <nuttx/config.h>
 
 #include <sys/socket.h>
+#include <netinet/in.h>
 
 #include <nuttx/net/ioctl.h>
 
@@ -57,6 +58,20 @@ struct rtentry
   FAR char *rt_dev;                   /* Forcing the device at add. */
 };
 
+struct in6_rtmsg
+{
+  struct in6_addr rtmsg_dst;
+  struct in6_addr rtmsg_src;
+  struct in6_addr rtmsg_gateway;
+  uint32_t rtmsg_type;
+  uint16_t rtmsg_dst_len;
+  uint16_t rtmsg_src_len;
+  uint32_t rtmsg_metric;
+  unsigned long int rtmsg_info;
+  uint32_t rtmsg_flags;
+  int rtmsg_ifindex;
+};
+
 /****************************************************************************
  * Public Data
  ****************************************************************************/