Fix:

error: ‘opt’ undeclared (first use in this function)
--- scamper/scamper_icmp6.c	28 Nov 2024 08:30:02 -0000	1.118
+++ scamper/scamper_icmp6.c	12 Dec 2024 12:28:23 -0000
@@ -697,7 +697,6 @@ SOCKET scamper_icmp6_open(const void *ad
   if(setsockopt_int(fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, 1) != 0)
     printerror(__func__, "could not set IPV6_RECVPKTINFO");
 #elif defined(IPV6_PKTINFO)
-  opt = 1;
   if(setsockopt_int(fd, IPPROTO_IPV6, IPV6_PKTINFO, 1) != 0)
     printerror(__func__, "could not set IPV6_PKTINFO");
 #endif
--- scamper/scamper_udp6.c	6 Sep 2024 01:34:54 -0000	1.81
+++ scamper/scamper_udp6.c	12 Dec 2024 12:28:23 -0000
@@ -485,7 +485,6 @@ SOCKET scamper_udp6_open(const void *add
   if(setsockopt_int(fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, 1) != 0)
     printerror(__func__, "could not set IPV6_RECVPKTINFO");
 #elif defined(IPV6_PKTINFO)
-  opt = 1;
   if(setsockopt_int(fd, IPPROTO_IPV6, IPV6_PKTINFO, 1) != 0)
     printerror(__func__, "could not set IPV6_PKTINFO");
 #endif