utils: Only check for xnnpack if torch installed (#74342)
Summary:
Fixes a bug where collect_env.py was not able to be run without having
torch installed
Signed-off-by: Eli Uriegas <eliuriegas@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/74342
Reviewed By: malfet, janeyx99
Differential Revision: D34943464
Pulled By: seemethere
fbshipit-source-id: dbaa0004b88cb643a9c6426c9ea7c5be3d3c9ef5
(cherry picked from commit 4f39ebb823f88df0c3902db15deaffc6ba481cb3)
