Make the shape interpreter actually advance past fixed length vectors. Closes #2613.

src/rt/rust_shape.h

@@ -923,7 +923,9 @@ public:
     void walk_fixedvec1(uint16_t n_elts, bool is_pod) {
         size_align sa = size_of::get(*this);
         ALIGN_TO(sa.alignment);
+        U next_dp = dp + (n_elts * sa.size);
         static_cast<T *>(this)->walk_fixedvec2(n_elts, sa.size, is_pod);
+        dp = next_dp;
     }
 
     void walk_box1() { DATA_SIMPLE(void *, walk_box2()); }

src/test/run-pass/fixed_length_vec_glue.rs

@@ -0,0 +1,6 @@
+fn main() {
+    let arr = [1,2,3]/3;
+    let struct = {a: 13u8, b: arr, c: 42};
+    let s = sys::log_str(struct);
+    assert(s == "(13, [1, 2, 3]/3, 42)");
+}