`go test` requires both config.go and the test files in the same
directory. For out-of-tree builds, config.go is normally not placed next
to the source files, so copy the tests to the build directory as a
workaround.
The integration tests reside in integration-tests directory. To run
integration tests, cd integration-tests, then run "go test". Tests
depends on https://github.com/bradfitz/http2.