crypto/tls: let HTTP/1.1 clients connect to servers with NextProtos "h2"

Fixes golang#46310

Change-Id: Idd5e30f05c439f736ae6f3904cbb9cc2ba772315
Reviewed-on: https://go-review.googlesource.com/c/go/+/325432
Trust: Filippo Valsorda <[email protected]>
Run-TryBot: Filippo Valsorda <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Roland Shoemaker <[email protected]>

[release-branch.go1.16] go1.16.5

Change-Id: Ibe47050481a01ec434f87db31048981e21fba1c3
Reviewed-on: https://go-review.googlesource.com/c/go/+/324552
Run-TryBot: David Chase <[email protected]>
Trust: David Chase <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>
TryBot-Result: Go Bot <[email protected]>

[release-branch.go1.15] go1.15.13

Change-Id: Ib0907538e78ef9b272be8858bc8b52c8b7d6c71a
Reviewed-on: https://go-review.googlesource.com/c/go/+/324551
Run-TryBot: David Chase <[email protected]>
Trust: David Chase <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>

[release-branch.go1.16] go1.16.4

Change-Id: I7fb3c30641332961819a79819c7567cf1dbe1ab1
Reviewed-on: https://go-review.googlesource.com/c/go/+/317649
Run-TryBot: Heschi Kreinick <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>
Trust: Carlos Amedee <[email protected]>
Trust: Heschi Kreinick <[email protected]>

[release-branch.go1.15] go1.15.12

Change-Id: I2d5e242a8324ae76e9d78b94cbc2825561b0c2de
Reviewed-on: https://go-review.googlesource.com/c/go/+/317650
Run-TryBot: Heschi Kreinick <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>
Trust: Carlos Amedee <[email protected]>
Trust: Heschi Kreinick <[email protected]>

[release-branch.go1.16] go1.16.3

Change-Id: Iace7cfec757a6d0bac25f729be5ecb2ae3b59d74
Reviewed-on: https://go-review.googlesource.com/c/go/+/306569
Run-TryBot: Dmitri Shuralyov <[email protected]>
Run-TryBot: Carlos Amedee <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: David Chase <[email protected]>
TryBot-Result: Go Bot <[email protected]>

[release-branch.go1.15] go1.15.11

Change-Id: I601bb0b69e8204055ce37150b50779818a339169
Reviewed-on: https://go-review.googlesource.com/c/go/+/306570
Run-TryBot: Carlos Amedee <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: David Chase <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>

[release-branch.go1.16] go1.16.2

Change-Id: I0513a9731e0e0d57bfeda0ffab1c5787edc916f8
Reviewed-on: https://go-review.googlesource.com/c/go/+/300969
Run-TryBot: Carlos Amedee <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Trust: Carlos Amedee <[email protected]>

[release-branch.go1.15] go1.15.10

Change-Id: Ib4e90da6307bb80be8b9d67e0efa35d9dd5dd463
Reviewed-on: https://go-review.googlesource.com/c/go/+/300970
Run-TryBot: Carlos Amedee <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Trust: Carlos Amedee <[email protected]>

[release-branch.go1.16-security] go1.16.1

Change-Id: I4999d72caf9462554a2a6f1d761244cafec34718
Reviewed-on: https://team-review.git.corp.google.com/c/golang/go-private/+/1014541
Reviewed-by: Katie Hockman <[email protected]>