BUILD: stream_interface: remove si_fd() and its references

si_fd() is not used a lot, and breaks builds on OpenBSD 5.2 which
defines this name for its own purpose. It's easy enough to remove
this one-liner function, so let's do it.
diff --git a/src/proto_http.c b/src/proto_http.c
index d768b87..8e96ae6 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -2392,7 +2392,7 @@
 			 * previously disabled it, otherwise we might cause the client
 			 * to delay next data.
 			 */
-			setsockopt(si_fd(&s->si[0]), IPPROTO_TCP, TCP_QUICKACK, &one, sizeof(one));
+			setsockopt(s->si[0].conn->t.sock.fd, IPPROTO_TCP, TCP_QUICKACK, &one, sizeof(one));
 		}
 #endif
 
@@ -3706,7 +3706,7 @@
 		if ((s->listener->options & LI_O_NOQUICKACK) &&
 		    ((msg->flags & HTTP_MSGF_TE_CHNK) ||
 		     (msg->body_len > req->buf->i - txn->req.eoh - 2)))
-			setsockopt(si_fd(&s->si[0]), IPPROTO_TCP, TCP_QUICKACK, &one, sizeof(one));
+			setsockopt(s->si[0].conn->t.sock.fd, IPPROTO_TCP, TCP_QUICKACK, &one, sizeof(one));
 #endif
 	}
 
@@ -7657,7 +7657,8 @@
 {
 	int max;
 	chunk_printf(&trash, "%08x:%s.%s[%04x:%04x]: ", t->uniq_id, t->be->id,
-		      dir, (unsigned  short)si_fd(t->req->prod), (unsigned short)si_fd(t->req->cons));
+		      dir, (unsigned  short)t->req->prod->conn->t.sock.fd,
+		     (unsigned short)t->req->cons->conn->t.sock.fd);
 
 	for (max = 0; start + max < end; max++)
 		if (start[max] == '\r' || start[max] == '\n')