Add socket factory support to udp_server.c
diff --git a/config.m4 b/config.m4
index 2bf302b..96ac558 100644
--- a/config.m4
+++ b/config.m4
@@ -130,6 +130,7 @@
     src/core/lib/iomgr/resolve_address_windows.c \
     src/core/lib/iomgr/resource_quota.c \
     src/core/lib/iomgr/sockaddr_utils.c \
+    src/core/lib/iomgr/socket_factory_posix.c \
     src/core/lib/iomgr/socket_mutator.c \
     src/core/lib/iomgr/socket_utils_common_posix.c \
     src/core/lib/iomgr/socket_utils_linux.c \