[nnc] Fix output restriding of size-1 dimensions (#58256)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/58256
Size-1 dims mess up our output restriding logic, because they're
technically "dense" no matter what stride the dimension has. In this example a
size-1 dim has stride 1, which causes all the indices to be taken mod 1 (i.e.,
all indices become 0). We work around this peculiar case by skipping size-1 in
our layout logic, since it has no impact on the rest of the tensor's indexing.
ghstack-source-id: 128932739
Test Plan:
new unit test, plus
```
buck test mode/dev //langtech/mobile/audio_stream_processor:audio_stream_processor_test -- --exact 'langtech/mobile/audio_stream_processor:audio_stream_processor_test - AudioStreamProcessorTest.DemucsReadWriteFloat'
```
Reviewed By: eellison
Differential Revision: D28424388
fbshipit-source-id: e33e39eef2a5bf2797bee78a5987558308b6d110
