[clang] [llvm] [PowerPC][ISelLowering] Support -mstack-protector-guard=tls (PR #110928)

[Keith Packard via cfe-commits]

keith-packard wrote:

btw, I'm testing this using Linux from https://git.kernel.org/pub/scm/linux/kernel/git/nathan/linux.git/log/?h=b4/powerpc-fix-stackprotector-test-clang

https://github.com/llvm/llvm-project/pull/110928