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

[Keith Packard via cfe-commits]

keith-packard wrote:

> With [my series to fix `arch/powerpc`](https://git.kernel.org/pub/scm/linux/kernel/git/nathan/linux.git/log/?h=b4/powerpc-fix-stackprotector-test-clang) for this implementation applied to Linux, `CONFIG_HAVE_STACKPROTECTOR` is properly set and the Linux kernel dump test module (LKDTM)’s `REPORT_STACK_CANARY` test works correctly for both 32-bit and 64-bit. I think with a PowerPC specific review, we should be ready to land this.

Stewart reviewed the PowerPC aspects of the patch (he used to work at IBM on OPAL, firmware for OpenPOWER systems).

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