Add support for concurrently reading from an HTTP/1 request body
while writing the response.
Normally, the HTTP/1 server automatically consumes any remaining
request body before starting to write a response, to avoid deadlocking
clients which attempt to write a complete request before reading the
response.
Add a ResponseController.EnableFullDuplex method which disables this
behavior.
For #15527
For #57786
Change-Id: Ie7ee8267d8333e9b32b82b9b84d4ad28ab8edf01
Reviewed-on: https://go-review.googlesource.com/c/go/+/472636
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Damien Neil <dneil@google.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
