net/http: update bundled http2, add TestServerKeepAlivesEnabled h1/h2 tests
Updates x/net/http2 to x/net git rev
6dfeb344 for:
http2: make Server respect http1 Server's SetKeepAlivesEnabled
https://golang.org/cl/33153
And adds a test in std.
Fixes #17717
Change-Id: I3ba000abb6f3f682261e105d8a4bb93bde6609fe
Reviewed-on: https://go-review.googlesource.com/33231
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tom Bergan <tombergan@google.com>