[c_compiler] runProcess additions

[dcharkes]

Makes runProcess consistent with the ones in https://dart-review.googlesource.com/c/sdk/+/267340.

[coveralls]

coverage: 99.472% (-0.4%) from 99.848%
when pulling 72d5604 on fix-run-process
into c614277 on main.

[auto-submit]

auto label is removed for dart-lang/native, pr: 46, due to This PR has not met approval requirements for merging. You are a member of dart-team and need 1 more review(s) in order to merge this PR.

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