Fix decl-after-statement in tap_darwin.c

Author: danielinux

src/port/posix/tap_darwin.c

@@ -72,6 +72,7 @@ static int tap_poll(struct wolfIP_ll_dev *ll, void *buf, uint32_t len)
     struct pollfd pfd;
     uint8_t tmp[LINK_MTU + AF_HDR_SIZE];
     ssize_t n;
+    size_t ip_len;
 
     if (utun_fd < 0)
         return -1;
@@ -91,7 +92,7 @@ static int tap_poll(struct wolfIP_ll_dev *ll, void *buf, uint32_t len)
     if (n <= AF_HDR_SIZE)
         return 0;
 
-    size_t ip_len = (size_t)(n - AF_HDR_SIZE);
+    ip_len = (size_t)(n - AF_HDR_SIZE);
     if (sizeof(struct eth_hdr) + ip_len > len)
         ip_len = len - sizeof(struct eth_hdr);