remove redundant --install_dir parameter in GEN_COMMAND (#18473)
Summary:
remove redundant --install_dir parameter in GEN_COMMAND, since "--install_dir parameter " already contained in ${GEN_COMMAND}.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/18473
Differential Revision: D14620193
Pulled By: ezyang
fbshipit-source-id: ee9953b5d055f4b8beb3557f95f6539051b0028a
