fix net/http caching of broken persistent connections

The net/http transport code is currently broken, it keeps broken
persistent connections in the cache if a write error happens during
h2 handshake.

This is documented in the upstream bug at:
golang/go#40213

The problem occurs because in the "go" compiler the http2 code is
imported into http as a bundle, with an additional "http2" prefix
applied.  This messes up the erringRoundTripper handling because
the name doesn't match.

The solution is to have the "go" compiler look for an interface
instead, so we add a new dummy function that doesn't actually do
anything and then the "go" compiler can check whether the specified
RoundTripper implements the dummy function.

Specifically for Kubernetes we need to update the http2 code in the
"vendor" subdirectory.  A separate change is being made in the "go"
compiler.

Partial-Bug: 1887438
Depends-On: https://review.opendev.org/c/starlingx/compile/+/780669
Signed-off-by: Chris Friesen <[email protected]>
Change-Id: I95dcbda879973524cd23b2a374537a675ce9435f

kubernetes/kubernetes/centos/files/fix_http2_erringroundtripper_handling.patch

@@ -0,0 +1,12 @@
+diff --git a/vendor/golang.org/x/net/http2/transport.go b/vendor/golang.org/x/net/http2/transport.go
+index aeac7d8..ec18648 100644
+--- a/vendor/golang.org/x/net/http2/transport.go
++++ b/vendor/golang.org/x/net/http2/transport.go
+@@ -2404,6 +2404,7 @@ func strSliceContains(ss []string, s string) bool {
+
+ type erringRoundTripper struct{ err error }
+
++func (rt erringRoundTripper) IsHTTP2ErringRoundtripper() {}
+ func (rt erringRoundTripper) RoundTrip(*http.Request) (*http.Response, error) { return nil, rt.err }
+
+ // gzipReader wraps a response body so it can lazily

kubernetes/kubernetes/centos/kubernetes.spec

@@ -57,6 +57,7 @@ Source33:       genmanpages.sh
 
 Patch1: 0001-Fix-pagesize-check-to-allow-for-options-already-endi.patch
 Patch2: kubelet-service-remove-docker-dependency.patch
+Patch3: fix_http2_erringroundtripper_handling.patch
 
 # It obsoletes cadvisor but needs its source code (literally integrated)
 Obsoletes:      cadvisor
@@ -838,6 +839,7 @@ Kubernetes client tools like kubectl
 %setup -q -n %{con_repo}-%{con_commit} -T -b 1
 %setup -q -n %{repo}-%{commit}
 %patch1 -p1
+%patch3 -p1
 
 # copy contrib folder
 mkdir contrib
@@ -873,6 +875,10 @@ export KUBE_EXTRA_GOPATH=$(pwd)/Godeps/_workspace
 %ifarch ppc64le
 export GOLDFLAGS='-linkmode=external'
 %endif
+
+# uncomment these two lines to build unoptimized binaries for debugging.
+# export GOLDFLAGS=""
+# export GOGCFLAGS="-N -l"
 make WHAT="cmd/kube-proxy cmd/kube-apiserver cmd/kube-controller-manager cmd/kubelet cmd/kubeadm cmd/kube-scheduler cmd/kubectl"
 
 # convert md to man