build: Always build in C++11 mode.

Change-Id: Id8c26bc5951a0b60c4f2f0868ad0167b2f0d56af
Refs: #2103
diff --git a/src/interest-table.hpp b/src/interest-table.hpp
index 288ed9b..d85661c 100644
--- a/src/interest-table.hpp
+++ b/src/interest-table.hpp
@@ -82,6 +82,9 @@
   bool
   erase(ndn::ConstBufferPtr digest);
 
+  void
+  quiteErase(ndn::ConstBufferPtr digest);
+
   const_iterator
   begin() const
   {