glsl: Eliminate ir_assignment::condition

Reformatting is left for the next commit.

v2: Remove assignments from the contructors. :face_palm:

Reviewed-by: Matt Turner <mattst88@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14573>

src/compiler/glsl/opt_array_splitting.cpp

@@ -416,8 +416,6 @@ ir_array_splitting_visitor::visit_leave(ir_assignment *ir)
             new(mem_ctx) ir_dereference_array(ir->rhs->clone(mem_ctx, NULL),
                                               new(mem_ctx) ir_constant(i));
 
-         assert(ir->get_condition() == NULL);
-
          ir_assignment *assign_i = new(mem_ctx) ir_assignment(lhs_i, rhs_i);
 
          ir->insert_before(assign_i);