structs that contain pointers work!

test.witx

@@ -19,6 +19,11 @@
     (field $first s32)
     (field $second s32)))
 
+(typename $pair_int_ptrs
+  (struct
+    (field $first (@witx const_pointer s32))
+    (field $second (@witx const_pointer s32))))
+
 (module $foo
   (@interface func (export "bar")
     (param $an_int u32)
@@ -38,4 +43,8 @@
     (param $an_pair $pair_ints)
     (result $error $errno)
     (result $doubled s64))
+  (@interface func (export "sum_of_pair_of_ptrs")
+    (param $an_pair $pair_int_ptrs)
+    (result $error $errno)
+    (result $doubled s64))
 )