Rollup merge of #47718 - malbarbo:env-home-dir, r=nikomatsakis
Rollup merge of #47718 - malbarbo:env-home-dir, r=nikomatsakis

Make run-pass/env-home-dir.rs test more robust

Remove the assumption that home_dir always returns Some.

This allows the test to be executed with [cross](https://github.com/japaric/cross).

aidancully/rust,graydon/rust,GBGamer/rust,graydon/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,GBGamer/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust