test/mem: fix error check

Fix incorrect errno variable used in memory autotest.
Use rte_errno instead.

Fixes: 086d426 ("test/mem: fix memory autotests on FreeBSD")
Cc: stable@dpdk.org

Signed-off-by: Jie Zhou <jizh@linux.microsoft.com>
Acked-by: Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>

app/test/test_memory.c

@@ -63,7 +63,7 @@ check_seg_fds(const struct rte_memseg_list *msl, const struct rte_memseg *ms,
 	/* we're able to get memseg fd - try getting its offset */
 	ret = rte_memseg_get_fd_offset_thread_unsafe(ms, &offset);
 	if (ret < 0) {
-		if (errno == ENOTSUP)
+		if (rte_errno == ENOTSUP)
 			return 1;
 		return -1;
 	}