[2/N] Enable Wunused-result, Wunused-variable and Wmissing-braces in torch targets (#110836)
This PR enables Wunused-result, Wunused-variable and Wmissing-braces because our code base is clean.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/110836
Approved by: https://github.com/Skylion007
