gvariant: Remove some unnecessary type assertions on a hot path

While checking the validity of a `GVariantTypeInfo` is good, this code
path is very hot, and I’ve never seen these assertions catch a bug in
practice.

Lean more towards the performance side of the performance/correctness
tradeoff in this case, by removing the assertions here.

They remain in place in a number of other `GVariantTypeInfo` code paths,
so invalid `GVariantTypeInfo` pointers should hopefully still be caught
quickly.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

glib/gvarianttypeinfo.c

@@ -247,8 +247,6 @@ g_variant_type_info_query (GVariantTypeInfo *info,
                            guint            *alignment,
                            gsize            *fixed_size)
 {
-  g_variant_type_info_check (info, 0);
-
   if (alignment)
     *alignment = info->alignment;