x/net/ipv4: add support for source-specific multicast socket options

[mikioh]

As per request at https://groups.google.com/d/msg/golang-nuts/6J-Howedc8M/GYEYR1QqQJYJ,
adding support for SSM makes sense to help (S,G) signaling required networks.

[gopherbot]

Comment 1:

CL https://golang.org/cl/104290043 mentions this issue.

[mikioh]

Comment 2:

This issue was updated by revision 7d8da7d.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/104290043

[gopherbot]

Comment 3:

CL https://golang.org/cl/101460043 mentions this issue.

[mikioh]

Comment 4:

Other BSD variants need to wait for their multicast refactor work for supporting both
ASM and SSM. Windows and Solaris would be another issue. Plan 9? unlikely.

[mikioh]

Comment 5:

This issue was updated by revision 0c7ddfa.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/101460043

[gopherbot]

Comment 6:

CL https://golang.org/cl/115350043 mentions this issue.

[mikioh]

Comment 7:

This issue was updated by revision d7566da.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/101460043
»»»
LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/115350043

[gopherbot]

Comment 8:

CL https://golang.org/cl/113660043 mentions this issue.

[mikioh]

Comment 9:

This issue was updated by revision 3bf75e6.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/104290043
»»»
LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/113660043

[mikioh]

Comment 10:

Labels changed: added repo-net, removed repo-main.

[gopherbot]

Comment 11:

CL https://golang.org/cl/174030043 mentions this issue.

[mikioh]

Comment 12:

This issue was closed by revision golang/net@a33e90a.

Status changed to Fixed.