socket.c error 'SO_REUSEPORT' undeclared

Hello developer of bind.
Sorry about poor my english.

I have a issue about building bind-9.14.1 with linux-2.6.34.13.

$ ./configure --with-openssl=/usr/local/ssl --disable-linux-caps && make
... snip ...
socket.c: In function 'isc_socket_bind':
socket.c:4480:40: error: 'SO_REUSEPORT' undeclared (first use in this function)
socket.c:4480:40: note: each undeclared identifier is reported only once for each function it appears in
make[3]: *** [socket.o] Error 1
make[3]: Leaving directory `/home/m-ito/tmp/bind-9.14.1/lib/isc/unix'
make[2]: *** [subdirs] Error 1
make[2]: Leaving directory `/home/m-ito/tmp/bind-9.14.1/lib/isc'
make[1]: *** [subdirs] Error 1
make[1]: Leaving directory `/home/m-ito/tmp/bind-9.14.1/lib'
make: *** [subdirs] Error 1

I searched `SO_REUSEPORT' in my system, but it has been comment-outed.

$ egrep -r SO_REUSEPORT /usr/include/
/usr/include/asm/socket.h:/* To add :#define SO_REUSEPORT 15 */
/usr/include/asm-i386/socket.h:/* To add :#define SO_REUSEPORT 15 */

I understand SO_REUSEPORT is implemented in linux-3.9 or later.

In bind-9.14.1/lib/isc/unix/socket.c, next code is controled to ignore in environment SO_REUSEPORT is not defined.

5335 #if defined(SO_REUSEPORT) && defined(__linux__)
5336         int sock, yes = 1;
5337         sock = socket(AF_INET, SOCK_DGRAM, 0);
5338         if (sock < 0) {
5339                 sock = socket(AF_INET6, SOCK_DGRAM, 0);
5340                 if (sock < 0) {
5341                         return;
5342                 }
5343         }               
5344         if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
5345                        (void *)&yes, sizeof(yes)) < 0)
5346         {
5347                 close(sock); 
5348                 return;
5349         } else if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT,
5350                               (void *)&yes, sizeof(yes)) < 0)
5351         {
5352                 close(sock);
5353                 return;
5354         }
5355         hasreuseport = true;
5356         close(sock);
5357 #endif

But next code is not controled at all.
I guess next code should be ignore too in environment SO_REUSEPORT is not defined.

4480                 if (setsockopt(sock->fd, SOL_SOCKET, SO_REUSEPORT,
4481                                (void *)&on, sizeof(on)) < 0)
4482                 {
4483                         UNEXPECTED_ERROR(__FILE__, __LINE__,
4484                                          "setsockopt(%d) failed", sock->fd);
4485                 }

I tried to edit simply like below and built it.

     #if defined(SO_REUSEPORT) && defined(__linux__)
4480                 if (setsockopt(sock->fd, SOL_SOCKET, SO_REUSEPORT,
4481                                (void *)&on, sizeof(on)) < 0)
4482                 {
4483                         UNEXPECTED_ERROR(__FILE__, __LINE__,
4484                                          "setsockopt(%d) failed", sock->fd);
4485                 }
     #endif

But it become not to responce after about few hours from invoke it.

I strongly hope to fix this issue in next version of bind.
Thank you.