Update build files.
diff --git a/config.m4 b/config.m4
index e4e4108..8ef95c0 100644
--- a/config.m4
+++ b/config.m4
@@ -230,6 +230,7 @@
     src/core/ext/client_config/client_config_plugin.c \
     src/core/ext/client_config/connector.c \
     src/core/ext/client_config/default_initial_connect_string.c \
+    src/core/ext/client_config/http_connect_handshaker.c \
     src/core/ext/client_config/initial_connect_string.c \
     src/core/ext/client_config/lb_policy.c \
     src/core/ext/client_config/lb_policy_factory.c \