util: use C99 declaration in the for-loop hash_table_foreach() macro

Signed-off-by: Eric Engestrom <eric@engestrom.ch>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>

src/compiler/glsl/opt_dead_code.cpp

@@ -50,7 +50,6 @@ do_dead_code(exec_list *instructions, bool uniform_locations_assigned)
 
    v.run(instructions);
 
-   struct hash_entry *e;
    hash_table_foreach(v.ht, e) {
       ir_variable_refcount_entry *entry = (ir_variable_refcount_entry *)e->data;