Use more C++17 features

Mainly structured bindings, inline variables, and class template
argument deduction, plus many more smaller things.

Change-Id: I810d17e0adb470426e4e30c898e03b3140ad052f
diff --git a/daemon/fw/retx-suppression-exponential.cpp b/daemon/fw/retx-suppression-exponential.cpp
index 114b491..6158120 100644
--- a/daemon/fw/retx-suppression-exponential.cpp
+++ b/daemon/fw/retx-suppression-exponential.cpp
@@ -24,14 +24,11 @@
  */
 
 #include "retx-suppression-exponential.hpp"
+#include "algorithm.hpp"
 
 namespace nfd {
 namespace fw {
 
-const RetxSuppressionExponential::Duration RetxSuppressionExponential::DEFAULT_INITIAL_INTERVAL = 10_ms;
-const RetxSuppressionExponential::Duration RetxSuppressionExponential::DEFAULT_MAX_INTERVAL = 250_ms;
-const float RetxSuppressionExponential::DEFAULT_MULTIPLIER = 2.0f;
-
 namespace {
 
 class PitInfo final : public StrategyInfo