src/go.mod: sync golang.org/x/net with h2_bundle.go

The bundle included changes from a commit after the one referred to by
the go.mod, probably due to cmd/bundle using the GOPATH source.

Identified with the new go/packages based cmd/bundle from CL 189818.

$ go get golang.org/x/net@461777fb6f
$ go mod tidy
$ go mod vendor
$ go generate net/http # with CL 189818

Also, updated the socks_bundle.go generate command to drop obsolete
options and match h2_bundle.go. It caused no output changes.

Updates #32031

Change-Id: I0322d4e842dbfdad749455111072ca4872a62ad4
Reviewed-on: https://go-review.googlesource.com/c/go/+/189897


Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>