fix clean target
fix clean target

kkirstein/proglang-playground,kkirstein/proglang-playground,kkirstein/proglang-playground,kkirstein/proglang-playground,kkirstein/proglang-playground,kkirstein/proglang-playground,kkirstein/proglang-playground,kkirstein/proglang-playground,kkirstein/proglang-playground,kkirstein/proglang-playground,kkirstein/proglang-playground,kkirstein/proglang-playground,kkirstein/proglang-playground