pw_stream: Fix use of shutdown on Windows

Bug: 309680612
Test: Verified sample-project-default-build-windows succeeds.
Test: Verified socket unit tests pass.
Test: See details in testing done comment in the code review.
Change-Id: I6d46b8f859c5ec5ad936eb3de73b3a701ac9542d
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/180401
Reviewed-by: Carlos Chinchilla <cachinchilla@google.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
Commit-Queue: Erik Staats <estaats@google.com>

pw_stream/socket_stream.cc

@@ -17,6 +17,7 @@
 #if defined(_WIN32) && _WIN32
 #include <winsock2.h>
 #include <ws2tcpip.h>
+#define SHUT_RDWR SD_BOTH
 #else
 #include <arpa/inet.h>
 #include <netdb.h>