[clang] [llvm] [NVPTX] Add ex2.approx bf16 support and cleanup intrinsic definition (PR #165446)

[Artem Belevich via cfe-commits]

================
@@ -375,28 +375,28 @@ static Value *MakeCpAsync(unsigned IntrinsicID, unsigned IntrinsicIDS,
                                        CGF.EmitScalarExpr(E->getArg(1))});
 }
 
-static Value *MakeHalfType(unsigned IntrinsicID, unsigned BuiltinID,
-                           const CallExpr *E, CodeGenFunction &CGF) {
+static bool EnsureNativeHalfSupport(unsigned BuiltinID, const CallExpr *E,
+                                    CodeGenFunction &CGF) {
   auto &C = CGF.CGM.getContext();
   if (!(C.getLangOpts().NativeHalfType ||
         !C.getTargetInfo().useFP16ConversionIntrinsics())) {
----------------
Artem-B wrote:

Nit: too many negations. May as well make it a bit easier to read while we're here:
```
if (!C.getLangOpts().NativeHalfType &&
        C.getTargetInfo().useFP16ConversionIntrinsics())) {
```

https://github.com/llvm/llvm-project/pull/165446