[clang] [Clang] Add __has_target_builtin macro (PR #126324)

[Joseph Huber via cfe-commits]

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@@ -357,6 +357,7 @@ void Preprocessor::RegisterBuiltinMacros() {
   Ident__has_builtin = RegisterBuiltinMacro("__has_builtin");
   Ident__has_constexpr_builtin =
       RegisterBuiltinMacro("__has_constexpr_builtin");
+  Ident__has_target_builtin = RegisterBuiltinMacro("__has_target_builtin");
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jhuber6 wrote:

Yeah, `__has_target_builtin()` is probably identical to `__has_builtin` on non-offloading related things. It's up to them if they keep it portable.

https://github.com/llvm/llvm-project/pull/126324