Fixing DecayDb visibility for windows shared build.

radixio/decaydb.hh

@@ -5,6 +5,8 @@
 #include <string>
 #include <unordered_map>
 
+#include "radixdl/visibility.hh"
+
 namespace radix
 {
 struct DecayDBEntry
@@ -111,7 +113,7 @@ struct DecayDBEntry
   int zaid() { return z * 10000 + a * 10 + m; }
 
 };  // struct
-class DecayDb
+class RADIX_PUBLIC DecayDb
 {
   std::unordered_map<int, DecayDBEntry> mActivation;
   std::unordered_map<int, DecayDBEntry> mActinide;