Fix websockets tests broken by switching Kestrel back to libuv by default

[natemcmaster]

Some tests started failing after aspnet/KestrelHttpServer#2257

• Microsoft.AspNetCore.WebSockets.Test
• Microsoft.AspNetCore.Proxy.Test.WebSocketsTest

http://aspnetci/viewLog.html?buildId=390091&tab=buildResultsDiv&buildTypeId=Lite_UniverseTest

cc @ryanbrandenburg

@halter73 can you take a look?

[natemcmaster]

Failure:

System.IO.IOException : Failed to bind to address http://localhost:4001.
---- System.AggregateException : One or more errors occurred.
-------- System.DllNotFoundException : Unable to load DLL 'libuv': The specified module could not be found. (Exception from HRESULT: 0x8007007E)

[halter73]

Fixed by aspnet/WebSockets@ec442c3

[analogrelay]

FYI, there are other tests (in Proxy) which have similar issues. And I'd imagine the various server/functional tests may have this issue to (depending on if they have the necessary MSBuild config applied). Perhaps we should try to put something in our common targets to enable this for all test projects. /cc @ryanbrandenburg @natemcmaster @halter73

[halter73]

👍 It doesn't hurt to add the HasRuntimeOutput to all the test projects until the vstest issue is fixed, right?

[analogrelay]

Yeah, that's what I suggested to @ryanbrandenburg earlier.