Restore the download of rust-mingw
Restore the download of rust-mingw

The build might otherwise break due to mixing MinGW object files from
rust-std and the local MinGW which might be newer/older than the version
used to build rust-std.

Fixes #48272

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