[llvm] Update the EBO static_assert to dheck against APFloat::Storage instead of IEEEFloat. (PR #112589)

[Jakub Kuderski via llvm-commits]

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@@ -99,6 +99,11 @@ enum class fltNanEncoding {
   NegativeZero,
 };
 
+class APFloatEBOChecker {
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kuhar wrote:

OK, that's fair. Could you add a comment explaining this next to the friend declaration?

https://github.com/llvm/llvm-project/pull/112589