[llvm] [RISCV] Adjust max stack-threshold on 64bit systems (PR #208223)

[Philipp Rados via llvm-commits]

prados-oc wrote:

Another thing I realized when skimming through StackColoring.cpp is that they seem to track stack-size as an unsigned in: https://github.com/llvm/llvm-project/blob/494697f79f5f7f6b40b78c8f49a98588ee87f1bd/llvm/lib/CodeGen/StackColoring.cpp#L1227
this wraps-around for both PPC and RISCV64, when the stack is bigger. In this case this could probably be simple fix, but I do wonder in how many other places this assumption is being made.

https://github.com/llvm/llvm-project/pull/208223