[libc] [llvm] [libc][NFC] Move float macro into its own header / add target os detection (PR #73311)

[Clement Courbet via llvm-commits]

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@@ -9,7 +9,7 @@
 #ifndef LLVM_LIBC_SRC_MATH_COPYSIGNF128_H
 #define LLVM_LIBC_SRC_MATH_COPYSIGNF128_H
 
-#include "src/__support/macros/properties/compiler.h"
+#include "src/__support/macros/properties/float.h"
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legrosbuffle wrote:

You probably want to add a cmake dep for this.

https://github.com/llvm/llvm-project/pull/73311