[llvm] [NFC] Various Cleanup in StackColoring, StackSlotColoring, LiveStacks (PR #143931)

[Matt Arsenault via llvm-commits]

================
@@ -581,6 +581,41 @@ onerr:
 
 %Data = type { [32 x i64] }
 
+declare void @throw()
----------------
arsenm wrote:

Refactoring change shouldn't have test changes? 

https://github.com/llvm/llvm-project/pull/143931