fix asan failure for module freezing in conv bn folding (#42739)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/42739
This is a test case which fails with ASAN on at the module freezing
step.
Test Plan:
```
USE_ASAN=1 USE_CUDA=0 python setup.py develop
LD_PRELOAD=/usr/lib64/libasan.so.4 python test/test_mobile_optimizer.py TestOptimizer.test_optimize_for_mobile_asan
// output tail: https://gist.github.com/vkuzo/7a0018b9e10ffe64dab0ac7381479f23
```
Imported from OSS
Reviewed By: kimishpatel
Differential Revision: D23005962
fbshipit-source-id: b7d4492e989af7c2e22197c16150812bd2dda7cc
