table: make FIB and StrategyChoice iterators default-constructible

They were previously not default-constructible when compiled with gcc 4.8.4.

refs #3882

Change-Id: I2431c869fb61b7adbe83d5551705981bf8618280
diff --git a/daemon/table/strategy-choice.cpp b/daemon/table/strategy-choice.cpp
index d801870..06acaae 100644
--- a/daemon/table/strategy-choice.cpp
+++ b/daemon/table/strategy-choice.cpp
@@ -26,6 +26,7 @@
 #include "strategy-choice.hpp"
 #include "measurements-entry.hpp"
 #include "pit-entry.hpp"
+#include "core/asserts.hpp"
 #include "core/logger.hpp"
 #include "fw/strategy.hpp"
 
@@ -34,6 +35,8 @@
 
 using fw::Strategy;
 
+NFD_ASSERT_FORWARD_ITERATOR(StrategyChoice::const_iterator);
+
 NFD_LOG_INIT("StrategyChoice");
 
 static inline bool