Use anonymous namespace for constants

src/engine/ebur128analysis.cpp

@@ -47,10 +47,10 @@
 
 using std::unique_ptr;
 
-static const int kTimeoutSecs = 60;
-
 namespace {
 
+constexpr int kTimeoutSecs = 60;
+
 struct ebur128_state_deleter {
   void operator()(ebur128_state *p) const { ebur128_destroy(&p); };
 };