[compiler-rt] [MSan] Fix check overflow in a test case (PR #150429)

[Kunqiu Chen via llvm-commits]

Camsyn wrote:

> Did this cause test failures for you?

I am implementing a sanitizer composition framework, which intends to support ASan, TSan and MSan.

This test failed in the scenario of `-fsanitie=address,memory`, where ASan modifies the size of this stack array.

https://github.com/llvm/llvm-project/pull/150429