util: Fix uninitalized variable to avoid garbage value.

This commit is similar with 596aa144. It fixes an uninitialized
variable to avoid garbage value. This case, it uses time 't' 0 if
an error occurs with virTimeMillisNowRaw.
Signed-off-by: NJulio Faracco <jcfaracco@gmail.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>

src/util/virtime.c

@@ -422,7 +422,7 @@ virTimeBackOffStart(virTimeBackOffVar *var,
 bool
 virTimeBackOffWait(virTimeBackOffVar *var)
 {
-    unsigned long long t, next;
+    unsigned long long next, t = 0;
 
     ignore_value(virTimeMillisNowRaw(&t));