THRIFT-4936 add depth limit type exception description
Client: C++
Patch: pengzhouhu

This closes #1852
diff --git a/lib/cpp/src/thrift/protocol/TProtocolException.h b/lib/cpp/src/thrift/protocol/TProtocolException.h
index 3d44365..4ace904 100644
--- a/lib/cpp/src/thrift/protocol/TProtocolException.h
+++ b/lib/cpp/src/thrift/protocol/TProtocolException.h
@@ -84,6 +84,8 @@
         return "TProtocolException: Invalid version";
       case NOT_IMPLEMENTED:
         return "TProtocolException: Not implemented";
+      case DEPTH_LIMIT:
+        return "TProtocolException: Exceeded depth limit";
       default:
         return "TProtocolException: (Invalid exception type)";
       }