Add shell=True to bootstrap's subprocess execution

[cengiz-io]

Fixes: #40529

I didn't test this with Windows so, we'll see how it goes.

Thanks!

[rust-highfive]

r? @alexcrichton

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[alexcrichton]

Hm this seems suspicious because I have a feeling that shell=True mucks around and spawns a process through a shell rather than the process directly (which is what we want). Notably this is required for ctrl-c to work on Windows.

It looks like the associated issue mentions you're running on Alpine, but I believe the compiler does not currently run successfully there due to the linkage against glibc instead of musl, right?