[llvm] [SPIR-V] Don't lower builtin variadic functions (PR #188517)

[Dmitry Sidorov via llvm-commits]

================
@@ -984,6 +993,29 @@ struct SPIRV final : public VariadicABIInfo {
     return {A, false};
   }
 
+  // The SPIR-V backend has special handling for builtins.
+  bool ignoreFunction(Function *F) override {
----------------
MrSidims wrote:

nit:
```suggestion
  bool ignoreFunction(const Function *F) override {
```

https://github.com/llvm/llvm-project/pull/188517