tests: Add missing 'static' attributes (fix warnings from smatch)

Smatch also complains about 0 used for pointers, so replace those by
NULL in test-visitor-serialization.c, too.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

1 files changed, 1 insertions, 1 deletions

diff --git a/tests/test-aio.c b/tests/test-aio.c
index 4c40a4971f..f12b6e0ae8 100644
--- a/tests/test-aio.c
+++ b/tests/test-aio.c
@@ -15,7 +15,7 @@
 #include "qemu/timer.h"
 #include "qemu/sockets.h"
 
-AioContext *ctx;
+static AioContext *ctx;
 
 typedef struct {
     EventNotifier e;