[clang] [clang][Driver] Fix safestack -u ordering (PR #98468)

[Rainer Orth via cfe-commits]

rorth wrote:

This patch was already approved in [ [safestack] Various Solaris fixes #98001 ](https://github.com/llvm/llvm-project/pull/98001), therefore I'll commit it shortly.

https://github.com/llvm/llvm-project/pull/98468