Fixed MOODYCAMEL_EXPORT being undefined on platforms other than Windows for the optional C API (issue cameron314#248)

Author: cameron314

c_api/concurrentqueue.h

@@ -13,10 +13,10 @@ extern "C" {
 #else
 #define MOODYCAMEL_EXPORT __declspec(dllimport)
 #endif
-#endif
 #else
 #define MOODYCAMEL_EXPORT
 #endif
+#endif
 
 typedef void* MoodycamelCQHandle;
 typedef void* MoodycamelBCQHandle;