glsl: Fix lower_named_interface_blocks to account for dereferences of consts.

In certain rare cases (such as those involving dereference of a
literal constant array of structs),
flatten_named_interface_blocks_declarations's rvalue visitor may be
invoked on an ir_dereference_record whose variable_referenced() method
returns NULL.

Check for this case to avoid a segfault.

Prevents crashes in piglit tests
{vs,fs}-deref-literal-array-of-structs.

Reviewed-by: Kenneth Graunke <[email protected]>
Reviewed-by: Jordan Justen <[email protected]>

0 files changed, 0 insertions, 0 deletions