[compiler-rt] [compiler-rt] [test] Work around MS CRT stdio format quirks on mingw too (PR #93787)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

This fixes test errors that I ran into in my nightly run, at https://github.com/mstorsjo/llvm-mingw/actions/runs/9295142303/job/25588557605.

https://github.com/llvm/llvm-project/pull/93787