nir/vtn: fix emitting code after loops

When we're done emitting the code for a loop, we need to visit the new
break block, which is the merge block of the current loop, rather than
the old merge block, which is the merge block of the loop containing the
one we just emitted code for.

src/glsl/nir/spirv_to_nir.c

@@ -2095,7 +2095,7 @@ vtn_walk_blocks(struct vtn_builder *b, struct vtn_block *start,
          vtn_walk_blocks(b, block, new_break_block, new_cont_block, NULL);
 
          nir_builder_insert_after_cf_list(&b->nb, old_list);
-         block = break_block;
+         block = new_break_block;
          continue;
       }