Small bug-fix to compile correctly when not in header only

The destructor of the registry is defaulted, which is equivalent to
inlining but if the default declaration is in the header, when compiling
the library, the forward declaration of the formatter is not being
resolved yet which doesn't allow a clean compilation

include/spdlog/details/registry-inl.h

@@ -47,6 +47,9 @@ SPDLOG_INLINE registry::registry()
 
 #endif // SPDLOG_DISABLE_DEFAULT_LOGGER
 }
+
+registry::~registry() = default;
+
 SPDLOG_INLINE void registry::register_logger(std::shared_ptr<logger> new_logger)
 {
     std::lock_guard<std::mutex> lock(logger_map_mutex_);

include/spdlog/details/registry.h

@@ -30,7 +30,7 @@ class registry
 public:
 	// Default constructor
 	registry();
-	~registry() = default;
+	~registry();
 
     registry(const registry &) = delete;
     registry &operator=(const registry &) = delete;