[llvm] [StackColoring] Change TotalStackSize from unsigned to int64_t (PR #208671)

[Philipp Rados via llvm-commits]

prados-oc wrote:

Not really sure who to ping for review here. Judging by the commit history of this pass:
cc @topperc @nikic 

https://github.com/llvm/llvm-project/pull/208671