Auto merge of #31331 - petevine:master, r=alexcrichton

The target was meant as a modern generic `armv7` option, therefore a few changes were necessary:

- gcc's `-march=armv7` was causing compilation failures on modern linux systems
- rust codegen defaulted to `cortex-a7` causing illegal instruction crashes on previous `armv7-a` processors (e.g, cortex-a5, cortex-a8)