Refactor queue

src/util.h

@@ -6,6 +6,12 @@
 #include "net.h"
 #include "str.h"
 
+#if MG_ENABLE_ASSERT
+#include <assert.h>
+#elif !defined(assert)
+#define assert(x)
+#endif
+
 void mg_random(void *buf, size_t len);
 char *mg_random_str(char *buf, size_t len);
 uint16_t mg_ntohs(uint16_t net);