glsl2: Fix validation for ir_unop_not.

We use vector ir_unop_not to implement builtin not(), and that seems fine.
diff --git a/src/glsl/ir_validate.cpp b/src/glsl/ir_validate.cpp
index 85417a1..1dfac82 100644
--- a/src/glsl/ir_validate.cpp
+++ b/src/glsl/ir_validate.cpp
@@ -171,8 +171,8 @@
       assert(ir->operands[0]->type == ir->type);
       break;
    case ir_unop_logic_not:
-      assert(ir->type == glsl_type::bool_type);
-      assert(ir->operands[0]->type == glsl_type::bool_type);
+      assert(ir->type->base_type == GLSL_TYPE_BOOL);
+      assert(ir->operands[0]->type->base_type == GLSL_TYPE_BOOL);
       break;
 
    case ir_unop_neg: