add back protobuf-c
diff --git a/.gitmodules b/.gitmodules
index 6bd3cc6..164c2bd 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -7,3 +7,6 @@
 [submodule "third_party/protobuf"]
 	path = third_party/protobuf
 	url = https://github.com/google/protobuf.git
+[submodule "third_party/protobuf-c"]
+	path = third_party/protobuf-c
+	url = https://github.com/shadansari/protobuf-c.git