[libclc] libclc: increase fp16 support (PR #98149)

[Fraser Cormack via cfe-commits]

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@@ -181,3 +181,15 @@ _CLC_OVERLOAD _CLC_DEF double atan(double x)
 _CLC_UNARY_VECTORIZE(_CLC_OVERLOAD _CLC_DEF, double, atan, double);
 
 #endif // cl_khr_fp64
+
+#ifdef cl_khr_fp16
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frasercrmck wrote:

Can this be `_CLC_DEFINE_UNARY_BUILTIN_FP16(atan)`?

https://github.com/llvm/llvm-project/pull/98149