re PR go/69966 (libgo: Port syscall.SetsockoptUcred from golang)

	PR go/69966
    syscall: Add new Getsockopt functions.
    
    Add GetsockoptICMPv6Filter, GetsockoptIPv6MTUInfo, GetsockoptUcred as
    appropriate.  These functions exist in the master library.
    
    For GCC PR 69966.

    Reviewed-on: https://go-review.googlesource.com/19960

From-SVN: r233747

gcc/go/gofrontend/MERGE

-156f5f0152797ac2afe5f23803aeb3c7b8f8418e
+3de822d11255d439fac9717897b017aae2de18c2
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/go/syscall/socket.go

@@ -251,6 +251,13 @@ func GetsockoptIPv6Mreq(fd, level, opt int) (*IPv6Mreq, error) {
 	return &value, err
 }
 
+func GetsockoptICMPv6Filter(fd, level, opt int) (*ICMPv6Filter, error) {
+	var value ICMPv6Filter
+	vallen := Socklen_t(SizeofICMPv6Filter)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
+	return &value, err
+}
+
 //sys	setsockopt(s int, level int, name int, val unsafe.Pointer, vallen Socklen_t) (err error)
 //setsockopt(s _C_int, level _C_int, optname _C_int, val *byte, vallen Socklen_t) _C_int
 

libgo/go/syscall/socket_bsd.go

@@ -80,3 +80,10 @@ func BindToDevice(fd int, device string) (err error) {
 func anyToSockaddrOS(rsa *RawSockaddrAny) (Sockaddr, error) {
 	return nil, EAFNOSUPPORT
 }
+
+func GetsockoptIPv6MTUInfo(fd, level, opt int) (*IPv6MTUInfo, error) {
+	var value IPv6MTUInfo
+	vallen := Socklen_t(SizeofIPv6MTUInfo)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
+	return &value, err
+}

libgo/go/syscall/socket_linux.go

@@ -168,6 +168,20 @@ func anyToSockaddrOS(rsa *RawSockaddrAny) (Sockaddr, error) {
 	return nil, EAFNOSUPPORT
 }
 
+func GetsockoptIPv6MTUInfo(fd, level, opt int) (*IPv6MTUInfo, error) {
+	var value IPv6MTUInfo
+	vallen := Socklen_t(SizeofIPv6MTUInfo)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
+	return &value, err
+}
+
+func GetsockoptUcred(fd, level, opt int) (*Ucred, error) {
+	var value Ucred
+	vallen := Socklen_t(SizeofUcred)
+	err := getsockopt(fd, level, opt, unsafe.Pointer(&value), &vallen)
+	return &value, err
+}
+
 //sysnb	EpollCreate(size int) (fd int, err error)
 //epoll_create(size _C_int) _C_int
 

libgo/mksysinfo.sh

@@ -870,6 +870,14 @@ if ! grep 'type ICMPv6Filter ' ${OUT} > /dev/null 2>&1; then
   echo 'type ICMPv6Filter struct { Data [8]uint32 }' >> ${OUT}
 fi
 
+# The ip6_mtuinfo struct.
+grep '^type _ip6_mtuinfo ' gen-sysinfo.go | \
+    sed -e 's/_ip6_mtuinfo/IPv6MTUInfo/' \
+      -e 's/ip6m_addr/Addr/' \
+      -e 's/_sockaddr_in6/RawSockaddrInet6/' \
+      -e 's/ip6m_mtu/Mtu/' \
+    >> ${OUT}
+
 # Try to guess the type to use for fd_set.
 fd_set=`grep '^type _fd_set ' gen-sysinfo.go || true`
 fds_bits_type="_C_long"
@@ -1464,7 +1472,7 @@ set cmsghdr Cmsghdr ip_mreq IPMreq ip_mreqn IPMreqn ipv6_mreq IPv6Mreq \
     msghdr Msghdr nlattr NlAttr nlmsgerr NlMsgerr nlmsghdr NlMsghdr \
     rtattr RtAttr rtgenmsg RtGenmsg rtmsg RtMsg rtnexthop RtNexthop \
     sock_filter SockFilter sock_fprog SockFprog ucred Ucred \
-    icmp6_filter ICMPv6Filter
+    icmp6_filter ICMPv6Filter ip6_mtuinfo IPv6MTUInfo
 while test $# != 0; do
     nc=$1
     ngo=$2