Add endpoint_pair_windows.c
diff --git a/build.json b/build.json
index 1e7ab96..06bcd0e 100644
--- a/build.json
+++ b/build.json
@@ -191,6 +191,7 @@
         "src/core/iomgr/alarm_heap.c",
         "src/core/iomgr/endpoint.c",
         "src/core/iomgr/endpoint_pair_posix.c",
+        "src/core/iomgr/endpoint_pair_windows.c",
         "src/core/iomgr/fd_posix.c",
         "src/core/iomgr/iocp_windows.c",
         "src/core/iomgr/iomgr.c",