Move enum class async_overflow_policy to backend_worker.h

include/spdlog/async_logger.h

@@ -19,14 +19,6 @@
 
 namespace spdlog {
 
-// Async overflow policy - block by default.
-enum class async_overflow_policy {
-    block,           // Block until message can be enqueued
-    overrun_oldest,  // Discard oldest message in the queue if full when trying to
-                     // add new item.
-    discard_new      // Discard new message if the queue is full when trying to add new item.
-};
-
 namespace details {
 class thread_pool;
 }

include/spdlog/details/backend_worker.h

@@ -3,11 +3,16 @@
 
 #pragma once
 
-
 namespace spdlog {
+// Async overflow policy - block by default.
+enum class async_overflow_policy {
+    block,           // Block until message can be enqueued
+    overrun_oldest,  // Discard oldest message in the queue if full when trying to
+                     // add new item.
+    discard_new      // Discard new message if the queue is full when trying to add new item.
+};
 
 namespace details {
-
 class thread_pool;
 
 class backend_worker : public std::enable_shared_from_this<backend_worker> {