Auto merge of #79685 - sivadeilra:fix_env_vars_win, r=davidtwco

Auto merge of #79685 - sivadeilra:fix_env_vars_win, r=davidtwco

Fix src/test/ui/env-vars.rs on 128-core machines on Windows

On Windows, the environment variable NUMBER_OF_PROCESSORS has special
meaning. Unfortunately, you can get different answers, depending on
whether you are enumerating all environment variables or querying a
specific variable. This was causing the src/test/ui/env-vars.rs test
to fail on machines with more than 64 processors when run on Windows.