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:
https://github.com/golang/go/issues/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.

This is slightly different from the proposed upstream fixes for the
above upstream bug, it more closely follows how the equivalent
problem was solved by IsHTTP2NoCachedConnError().

Change-Id: Ia6e91acb15ff4fe996c8ea9b8a1032cede6c4aab
Partial-Bug: 1887438
Signed-off-by: Chris Friesen <chris.friesen@windriver.com>