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/test/cpp/qps/server_async.cc b/test/cpp/qps/server_async.cc
index 19778e5..121ac73 100644
--- a/test/cpp/qps/server_async.cc
+++ b/test/cpp/qps/server_async.cc
@@ -68,7 +68,7 @@
     gpr_join_host_port(&server_address, "::", port);
 
     ServerBuilder builder;
-    builder.AddPort(server_address, InsecureServerCredentials());
+    builder.AddListeningPort(server_address, InsecureServerCredentials());
     gpr_free(server_address);
 
     builder.RegisterAsyncService(&async_service_);