qtmux: Write uint tags that don't have a complement

Write uint tags that have complements (e.g. track-number/
track-count) even when we only have one of them available
and set the other one to 0.

Fixes #622484
diff --git a/gst/quicktime/gstqtmux.c b/gst/quicktime/gstqtmux.c
index ce5a433..6d2b30f 100644
--- a/gst/quicktime/gstqtmux.c
+++ b/gst/quicktime/gstqtmux.c
@@ -428,13 +428,13 @@
     }
     case G_TYPE_UINT:
     {
-      guint value;
+      guint value = 0;
       if (tag2) {
         /* paired unsigned integers */
-        guint count;
+        guint count = 0;
 
-        if (!gst_tag_list_get_uint (list, tag, &value) ||
-            !gst_tag_list_get_uint (list, tag2, &count))
+        if (!(gst_tag_list_get_uint (list, tag, &value) ||
+                gst_tag_list_get_uint (list, tag2, &count)))
           break;
         GST_DEBUG_OBJECT (qtmux, "Adding tag %" GST_FOURCC_FORMAT " -> %u/%u",
             GST_FOURCC_ARGS (fourcc), value, count);