Use g_strdup_vprintf() instead of virVasprintf() everywhere

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>

tests/eventtest.c

@@ -89,8 +89,8 @@ testEventReport(const char *name, bool failed, const char *msg, ...)
     char *str = NULL;
     struct testEventResultData data;
 
-    if (msg && virVasprintfQuiet(&str, msg, vargs) != 0)
-        failed = true;
+    if (msg)
+        str = g_strdup_vprintf(msg, vargs);
 
     data.failed = failed;
     data.msg = str;