Various Windows fixes.

-) using dupenv_s instead of getenv_s and calling strdup ourselves.
-) few impossible-to-obtain if checks.
-) various signed/unsigned casting.
-) using time_t instead of time32_t
-) checking output of FormatMessage for failures.
-) don't redefine _WIN32_WINNT without undefining it first.
-) fixed msvc's interlocked casting.
-) renamed AddPort to AddListeningPort.
-) added protobuf's third_party includes to search path.
-) added a missing definition for inet_ntop in mingw32.
-) removed useless declarations.
diff --git a/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs b/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs
index 814f631..1e76d3d 100644
--- a/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs
+++ b/src/csharp/Grpc.IntegrationTesting/InteropClientServerTest.cs
@@ -59,7 +59,7 @@
 
             server = new Server();
             server.AddServiceDefinition(TestServiceGrpc.BindService(new TestServiceImpl()));
-            int port = server.AddPort(host + ":0", TestCredentials.CreateTestServerCredentials());
+            int port = server.AddListeningPort(host + ":0", TestCredentials.CreateTestServerCredentials());
             server.Start();
 
             var channelArgs = ChannelArgs.CreateBuilder()
diff --git a/src/csharp/Grpc.IntegrationTesting/InteropServer.cs b/src/csharp/Grpc.IntegrationTesting/InteropServer.cs
index 5e58028..ad52007 100644
--- a/src/csharp/Grpc.IntegrationTesting/InteropServer.cs
+++ b/src/csharp/Grpc.IntegrationTesting/InteropServer.cs
@@ -96,11 +96,11 @@
             string addr = "0.0.0.0:" + options.port;
             if (options.useTls)
             {
-                server.AddPort(addr, TestCredentials.CreateTestServerCredentials());
+                server.AddListeningPort(addr, TestCredentials.CreateTestServerCredentials());
             }
             else
             {
-                server.AddPort(addr);
+                server.AddListeningPort(addr);
             }
             Console.WriteLine("Running server on " + addr);
             server.Start();