Fix test_u_async_comprehensive.c: replace POSIX headers with platform_compat.h

tests/test_u_async_comprehensive.c

@@ -7,12 +7,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
-#include <unistd.h>
-#include <sys/socket.h>
-#include <netinet/in.h>
-#include <arpa/inet.h>
-#include <fcntl.h>
-#include <errno.h>
+#include "../lib/platform_compat.h"
 
 #include "u_async.h"
 #include "timeout_heap.h"