[clang] [clang][CodeGen] Emit prefetch hints and frame address depth as i32 (PR #221477)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

The reason to do the conversions first is that sometimes you can't evaluate the unconverted value.  For example, you can do `struct S { int x; constexpr operator unsigned int() const { return x; } }; constexpr S x = {1}; void *f() { return __builtin_frame_address(x);}`.

https://github.com/llvm/llvm-project/pull/221477