Point protobuf-c to forked repo to fix compile error
diff --git a/.gitmodules b/.gitmodules
index 411fab3..9448016 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -6,7 +6,7 @@
 	url = https://github.com/grpc/grpc.git
 [submodule "third_party/protobuf-c"]
 	path = third_party/protobuf-c
-	url = https://github.com/protobuf-c/protobuf-c.git
+	url = https://github.com/shadansari/protobuf-c.git
 [submodule "third_party/protobuf"]
 	path = third_party/protobuf
 	url = https://github.com/google/protobuf.git