daemon: use asio::defer() instead of asio::post() where appropriate

Change-Id: I24d0fab6499d6430dd500ca157daa87f48960d15
diff --git a/tests/tools/mock-nfd-mgmt-fixture.hpp b/tests/tools/mock-nfd-mgmt-fixture.hpp
index ede5568..eed9846 100644
--- a/tests/tools/mock-nfd-mgmt-fixture.hpp
+++ b/tests/tools/mock-nfd-mgmt-fixture.hpp
@@ -34,6 +34,7 @@
 #include <ndn-cxx/mgmt/nfd/control-response.hpp>
 #include <ndn-cxx/util/dummy-client-face.hpp>
 
+#include <boost/asio/defer.hpp>
 #include <boost/concept/assert.hpp>
 
 namespace nfd::tests {
@@ -52,7 +53,7 @@
   {
     face.onSendInterest.connect([this] (const Interest& interest) {
       if (processInterest) {
-        m_io.post([=] { processInterest(interest); });
+        boost::asio::defer(m_io, [=] { processInterest(interest); });
       }
     });
   }