TUN-4597: Add a QUIC server skeleton

- Added a QUIC server to accept streams
- Unit test for this server also tests ALPN
- Temporary echo capability for HTTP ConnectionType

vendor/golang.org/x/net/ipv6/zsys_openbsd.go

@@ -4,56 +4,11 @@
 package ipv6
 
 const (
-	sysIPV6_UNICAST_HOPS   = 0x4
-	sysIPV6_MULTICAST_IF   = 0x9
-	sysIPV6_MULTICAST_HOPS = 0xa
-	sysIPV6_MULTICAST_LOOP = 0xb
-	sysIPV6_JOIN_GROUP     = 0xc
-	sysIPV6_LEAVE_GROUP    = 0xd
-	sysIPV6_PORTRANGE      = 0xe
-	sysICMP6_FILTER        = 0x12
-
-	sysIPV6_CHECKSUM = 0x1a
-	sysIPV6_V6ONLY   = 0x1b
-
-	sysIPV6_RTHDRDSTOPTS = 0x23
-
-	sysIPV6_RECVPKTINFO  = 0x24
-	sysIPV6_RECVHOPLIMIT = 0x25
-	sysIPV6_RECVRTHDR    = 0x26
-	sysIPV6_RECVHOPOPTS  = 0x27
-	sysIPV6_RECVDSTOPTS  = 0x28
-
-	sysIPV6_USE_MIN_MTU = 0x2a
-	sysIPV6_RECVPATHMTU = 0x2b
-
-	sysIPV6_PATHMTU = 0x2c
-
+	sysIPV6_PATHMTU  = 0x2c
 	sysIPV6_PKTINFO  = 0x2e
 	sysIPV6_HOPLIMIT = 0x2f
 	sysIPV6_NEXTHOP  = 0x30
-	sysIPV6_HOPOPTS  = 0x31
-	sysIPV6_DSTOPTS  = 0x32
-	sysIPV6_RTHDR    = 0x33
-
-	sysIPV6_AUTH_LEVEL        = 0x35
-	sysIPV6_ESP_TRANS_LEVEL   = 0x36
-	sysIPV6_ESP_NETWORK_LEVEL = 0x37
-	sysIPSEC6_OUTSA           = 0x38
-	sysIPV6_RECVTCLASS        = 0x39
-
-	sysIPV6_AUTOFLOWLABEL = 0x3b
-	sysIPV6_IPCOMP_LEVEL  = 0x3c
-
 	sysIPV6_TCLASS   = 0x3d
-	sysIPV6_DONTFRAG = 0x3e
-	sysIPV6_PIPEX    = 0x3f
-
-	sysIPV6_RTABLE = 0x1021
-
-	sysIPV6_PORTRANGE_DEFAULT = 0x0
-	sysIPV6_PORTRANGE_HIGH    = 0x1
-	sysIPV6_PORTRANGE_LOW     = 0x2
 
 	sizeofSockaddrInet6 = 0x1c
 	sizeofInet6Pktinfo  = 0x14