[compiler-rt] Add extendhfxf2 into compiler rt (PR #113897)

[Alexander Richardson via llvm-commits]

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@@ -0,0 +1,71 @@
+// RUN: %clang_builtins %s %librt -o %t && %run %t
+// REQUIRES: librt_has_extendhfxf2
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arichardson wrote:

Not needed with the correct #if guard.

https://github.com/llvm/llvm-project/pull/113897