DERP doesn't support HTTP/2. If an HTTP/2 proxy was placed in front of
a DERP server requests would fail because the connection would
be initialized with HTTP/2, which the DERP client doesn't support.
Signed-off-by: Kyle Carberry <kyle@carberry.com>
This fixes a race condition which caused `c.muCond.Broadcast()` to
never fire in the `firstDerp` if block. It resulted in `Close()`
hanging forever.
Signed-off-by: Kyle Carberry <kyle@carberry.com>